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89-459: Lustre ( British English ) or luster ( American English ; see spelling differences ) is the way light interacts with the surface of a crystal , rock , or mineral . The word traces its origins back to the Latin lux , meaning "light", and generally implies radiance, gloss, or brilliance. A range of terms are used to describe lustre, such as earthy , metallic , greasy , and silky . Similarly,

178-412: A Lambertian reflector . An example is kaolinite . A distinction is sometimes drawn between dull minerals and earthy minerals, with the latter being coarser, and having even less lustre. Greasy minerals resemble fat or grease. A greasy lustre often occurs in minerals containing a great abundance of microscopic inclusions, with examples including opal and cordierite , jadeite . Many minerals with

267-565: A West Germanic language that originated from the Anglo-Frisian dialects brought to Britain by Germanic settlers from various parts of what is now northwest Germany and the northern Netherlands. The resident population at this time was generally speaking Common Brittonic —the insular variety of Continental Celtic , which was influenced by the Roman occupation. This group of languages ( Welsh , Cornish , Cumbric ) cohabited alongside English into

356-436: A dissolution and reprecipitation mechanism, with the reaction rate controlled by the surface area of a calcite crystal. The second stage of the reaction is approximately 10 times slower. However, crystallization of calcite has been observed to be dependent on the starting pH and concentration of magnesium in solution. A neutral starting pH during mixing promotes the direct transformation of ACC into calcite without

445-531: A goniometer , and looking for the smallest numbers that fit. Later, a "structural" unit cell was determined using X-ray crystallography . The morphological unit cell is rhombohedral , having approximate dimensions a = 10 Å and c = 8.5 Å , while the structural unit cell is hexagonal (i.e. a rhombic prism ), having approximate dimensions a = 5 Å and c = 17 Å . For the same orientation, c must be multiplied by 4 to convert from morphological to structural units. As an example, calcite cleavage

534-527: A specific gravity of 2.71 and, in crystalline varieties, a vitreous luster . Color is white or none, though shades of gray, red, orange, yellow, green, blue, violet, brown, or even black can occur when the mineral is charged with impurities. Calcite has numerous habits, representing combinations of over 1000 crystallographic forms . Most common are scalenohedra , with faces in the hexagonal {2 1 1} directions (morphological unit cell) or {2 1 4} directions (structural unit cell); and rhombohedral, with faces in

623-549: A century as Received Pronunciation (RP). However, due to language evolution and changing social trends, some linguists argue that RP is losing prestige or has been replaced by another accent, one that the linguist Geoff Lindsey for instance calls Standard Southern British English. Others suggest that more regionally-oriented standard accents are emerging in England. Even in Scotland and Northern Ireland, RP exerts little influence in

712-607: A clear piece of calcite to appear doubled. The birefringent effect (using calcite) was first described by the Danish scientist Rasmus Bartholin in 1669. At a wavelength of about 590 nm, calcite has ordinary and extraordinary refractive indices of 1.658 and 1.486, respectively. Between 190 and 1700 nm, the ordinary refractive index varies roughly between 1.9 and 1.5, while the extraordinary refractive index varies between 1.6 and 1.4. Calcite has thermoluminescent properties mainly due to manganese divalent ( Mn ). An experiment

801-504: A greasy lustre also feel greasy to the touch. Metallic (or splendent ) minerals have the lustre of polished metal, and with ideal surfaces will work as a reflective surface . Examples include galena , pyrite and magnetite . Pearly minerals consist of thin transparent co-planar sheets. Light reflecting from these layers give them a lustre reminiscent of pearls . Such minerals possess perfect cleavage , with examples including muscovite and stilbite . Resinous minerals have

890-501: A greater movement, normally [əʊ], [əʉ] or [əɨ]. Dropping a morphological grammatical number , in collective nouns , is stronger in British English than North American English. This is to treat them as plural when once grammatically singular, a perceived natural number prevails, especially when applying to institutional nouns and groups of people. The noun 'police', for example, undergoes this treatment: Police are investigating

979-406: A lesser class or social status and often discounted or considered of a low intelligence. Another contribution to the standardisation of British English was the introduction of the printing press to England in the mid-15th century. In doing so, William Caxton enabled a common language and spelling to be dispersed among the entirety of England at a much faster rate. Samuel Johnson's A Dictionary of

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1068-405: A monohydrocalcite intermediate, sequestering carbon . Calcite is often the primary constituent of the shells of marine organisms , such as plankton (such as coccoliths and planktic foraminifera ), the hard parts of red algae , some sponges , brachiopods , echinoderms , some serpulids , most bryozoa , and parts of the shells of some bivalves (such as oysters and rudists ). Calcite

1157-436: A particular mineral species). The terms are frequently combined to describe intermediate types of lustre (for example, a "vitreous greasy" lustre). Some minerals exhibit unusual optical phenomena, such as asterism (the display of a star-shaped luminous area) or chatoyancy (the display of luminous bands, which appear to move as the specimen is rotated). A list of such phenomena is given below. Adamantine minerals possess

1246-648: A process called T-glottalisation . National media, being based in London, have seen the glottal stop spreading more widely than it once was in word endings, not being heard as "no [ʔ] " and bottle of water being heard as "bo [ʔ] le of wa [ʔ] er". It is still stigmatised when used at the beginning and central positions, such as later , while often has all but regained /t/ . Other consonants subject to this usage in Cockney English are p , as in pa [ʔ] er and k as in ba [ʔ] er. In most areas of England and Wales, outside

1335-511: A regional accent or dialect. However, about 2% of Britons speak with an accent called Received Pronunciation (also called "the King's English", "Oxford English" and " BBC English" ), that is essentially region-less. It derives from a mixture of the Midlands and Southern dialects spoken in London in the early modern period. It is frequently used as a model for teaching English to foreign learners. In

1424-581: A superlative lustre, which is most notably seen in diamond . Such minerals are transparent or translucent, and have a high refractive index (of 1.9 or more). Minerals with a true adamantine lustre are uncommon, with examples including cerussite , zircon , and cubic zirconia . Minerals with a lesser (but still relatively high) degree of lustre are referred to as subadamantine , with some examples being garnet and corundum . Dull (or earthy ) minerals exhibit little to no lustre, due to coarse granulations which scatter light in all directions, approximating

1513-526: A vaterite intermediate. But when ACC forms in a solution with a basic initial pH, the transformation to calcite occurs via metastable vaterite, following the pathway outlined above. Magnesium has a noteworthy effect on both the stability of ACC and its transformation to crystalline CaCO 3 , resulting in the formation of calcite directly from ACC, as this ion destabilizes the structure of vaterite. Epitaxial overgrowths of calcite precipitated on weathered cleavage surfaces have morphologies that vary with

1602-725: Is also due to London-centric influences. Examples of R-dropping are car and sugar , where the R is not pronounced. British dialects differ on the extent of diphthongisation of long vowels, with southern varieties extensively turning them into diphthongs, and with northern dialects normally preserving many of them. As a comparison, North American varieties could be said to be in-between. Long vowels /iː/ and /uː/ are usually preserved, and in several areas also /oː/ and /eː/, as in go and say (unlike other varieties of English, that change them to [oʊ] and [eɪ] respectively). Some areas go as far as not diphthongising medieval /iː/ and /uː/, that give rise to modern /aɪ/ and /aʊ/; that is, for example, in

1691-522: Is based on British English, but has more influence from American English , often grouped together due to their close proximity. British English, for example, is the closest English to Indian English, but Indian English has extra vocabulary and some English words are assigned different meanings. Calcite Other polymorphs of calcium carbonate are the minerals aragonite and vaterite . Aragonite will change to calcite over timescales of days or less at temperatures exceeding 300 °C, and vaterite

1780-441: Is designed to promote sustainable development in the mining industry. Calcite can help synthesize precipitated calcium carbonate (PCC) (mainly used in the paper industry) and increase carbonation . Furthermore, due to its particular crystal habit, such as rhombohedron, hexagonal prism, etc., it promotes the production of PCC with specific shapes and particle sizes. Calcite, obtained from an 80 kg sample of Carrara marble ,

1869-437: Is divided into low-magnesium and high-magnesium calcite, with the dividing line placed at a composition of 4% magnesium. High-magnesium calcite retains the calcite mineral structure, which is distinct from that of dolomite , MgCa(CO 3 ) 2 . Calcite can also contain small quantities of iron and manganese . Manganese may be responsible for the fluorescence of impure calcite, as may traces of organic compounds. Calcite

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1958-514: Is even less stable. Calcite is derived from the German Calcit , a term from the 19th century that came from the Latin word for lime , calx (genitive calcis ) with the suffix -ite used to name minerals. It is thus a doublet of the word chalk . When applied by archaeologists and stone trade professionals, the term alabaster is used not just as in geology and mineralogy, where it

2047-741: Is found all over the world, and its leading global distribution is as follows: Calcite is found in many different areas in the United States. One of the best examples is the Calcite Quarry in Michigan. The Calcite Quarry is the largest carbonate mine in the world and has been in use for more than 85 years. Large quantities of calcite can be mined from these sizeable open pit mines. Calcite can also be found throughout Canada, such as in Thorold Quarry and Madawaska Mine, Ontario, Canada. Abundant calcite

2136-459: Is found in spectacular form in the Snowy River Cave of New Mexico as mentioned above, where microorganisms are credited with natural formations. Trilobites , which became extinct a quarter billion years ago , had unique compound eyes that used clear calcite crystals to form the lenses. It also forms a substantial part of birds' eggshells, and the δ C of the diet is reflected in the δ C of

2225-407: Is given as "perfect on {1 0 1 1}" in morphological coordinates and "perfect on {1 0 1 4}" in structural units. In { h k l } {\displaystyle \{hkl\}} indices, these are {1 0 1} and {1 0 4}, respectively. Twinning , cleavage and crystal forms are often given in morphological units. The diagnostic properties of calcite include a defining Mohs hardness of 3,

2314-769: Is included in style guides issued by various publishers including The Times newspaper, the Oxford University Press and the Cambridge University Press . The Oxford University Press guidelines were originally drafted as a single broadsheet page by Horace Henry Hart, and were at the time (1893) the first guide of their type in English; they were gradually expanded and eventually published, first as Hart's Rules , and in 2002 as part of The Oxford Manual of Style . Comparable in authority and stature to The Chicago Manual of Style for published American English ,

2403-757: Is mined in the Santa Eulalia mining district, Chihuahua, Mexico. Large quantities of calcite in Iceland are concentrated in the Helgustadir mine . The mine was once the primary mining location of "Iceland spar." However, it currently serves as a nature reserve, and calcite mining will not be allowed. Calcite is found in parts of England, such as Alston Moor, Egremont, and Frizington, Cumbria. St. Andreasberg, Harz Mountains, and Freiberg, Saxony can find calcite. Ancient Egyptians carved many items out of calcite, relating it to their goddess Bast , whose name contributed to

2492-554: Is one of the minerals that has been shown to catalyze an important biological reaction, the formose reaction , and may have had a role in the origin of life. Interaction of its chiral surfaces (see Form ) with aspartic acid molecules results in a slight bias in chirality; this is one possible mechanism for the origin of homochirality in living cells. Climate change is exacerbating ocean acidification , possibly leading to lower natural calcite production. The oceans absorb large amounts of CO 2 from fossil fuel emissions into

2581-501: Is reserved for a variety of gypsum ; but also for a similar-looking, translucent variety of fine-grained banded deposit of calcite. In publications, two different sets of Miller indices are used to describe directions in hexagonal and rhombohedral crystals, including calcite crystals: three Miller indices h, k, l in the a 1 , a 2 , c {\displaystyle a_{1},a_{2},c} directions, or four Bravais–Miller indices h, k, i, l in

2670-524: Is responsible for alexandrite's characteristic green to red colour change. Alexandrite from the Ural Mountains in Russia is green by daylight and red by incandescent light. Other varieties of alexandrite may be yellowish or pink in daylight and a columbine or raspberry red by incandescent light. The optimum or "ideal" colour change would be fine emerald green to fine purplish red, but this is rare. Iridescence

2759-426: Is the 'play' or 'fire' of rainbow-coloured light caused by very thin regular structures or layers beneath the surface of a gemstone. Similar to a thin film of oil on water, these layers interfere with the rays of reflected light, reinforcing some colours and cancelling others. Iridescence is seen at its best in precious opal . Schiller (German, literally "shimmer"), is the metallic iridescence originating from below

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2848-430: Is the display of a star-shaped luminous area. It is seen in some sapphires and rubies , where it is caused by impurities of rutile . It can also occur in garnet , diopside and spinel . Aventurescence (or aventurization ) is a reflectance effect like that of glitter . It arises from minute, preferentially oriented mineral platelets within the material. These platelets are so numerous that they also influence

2937-403: Is the leading cause of excessive growth of cyanobacteria. As an active capping material, calcite can help reduce P release from sediments into the water, thus inhibiting cyanobacteria overgrowth. Calcite is a common constituent of sedimentary rocks , limestone in particular, much of which is formed from the shells of dead marine organisms. Approximately 10% of sedimentary rock is limestone. It

3026-474: Is the primary mineral in metamorphic marble . It also occurs in deposits from hot springs as a vein mineral; in caverns as stalactites and stalagmites ; and in volcanic or mantle-derived rocks such as carbonatites , kimberlites , or rarely in peridotites . Cacti contain Ca-oxalate biominerals. Their death releases these biominerals into the environment, which subsequently transform to calcite via

3115-586: Is used as the IAEA -603 isotopic standard in mass spectrometry for the calibration of δ O and δ C . Calcite can be formed naturally or synthesized. However, artificial calcite is the preferred material to be used as a scaffold in bone tissue engineering due to its controllable and repeatable properties. Calcite can be used to alleviate water pollution caused by the excessive growth of cyanobacteria . Lakes and rivers can lead to cyanobacteria blooms due to eutrophication , which pollutes water resources. Phosphorus (P)

3204-524: Is used for optical purposes. Acute scalenohedral crystals are sometimes referred to as "dogtooth spar" while the rhombohedral form is sometimes referred to as "nailhead spar". The rhombohedral form may also have been the " sunstone " whose use by Viking navigators is mentioned in the Icelandic Sagas . Single calcite crystals display an optical property called birefringence (double refraction). This strong birefringence causes objects viewed through

3293-471: The a 1 , a 2 , a 3 , c {\displaystyle a_{1},a_{2},a_{3},c} directions, where i {\displaystyle i} is redundant but useful in visualizing permutation symmetries . To add to the complications, there are also two definitions of unit cell for calcite. One, an older "morphological" unit cell, was inferred by measuring angles between faces of crystals, typically with

3382-530: The Chambers Dictionary , and the Collins Dictionary record actual usage rather than attempting to prescribe it. In addition, vocabulary and usage change with time; words are freely borrowed from other languages and other varieties of English, and neologisms are frequent. For historical reasons dating back to the rise of London in the ninth century, the form of language spoken in London and

3471-637: The East Midlands became standard English within the Court, and ultimately became the basis for generally accepted use in the law, government, literature and education in Britain. The standardisation of British English is thought to be from both dialect levelling and a thought of social superiority. Speaking in the Standard dialect created class distinctions; those who did not speak the standard English would be considered of

3560-558: The English language in England , or, more broadly, to the collective dialects of English throughout the British Isles taken as a single umbrella variety, for instance additionally incorporating Scottish English , Welsh English , and Northern Irish English . Tom McArthur in the Oxford Guide to World English acknowledges that British English shares "all the ambiguities and tensions [with]

3649-484: The Royal Spanish Academy with Spanish. Standard British English differs notably in certain vocabulary, grammar, and pronunciation features from standard American English and certain other standard English varieties around the world. British and American spelling also differ in minor ways. The accent, or pronunciation system, of standard British English, based in southeastern England, has been known for over

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3738-486: The Scots language or Scottish Gaelic ). Each group includes a range of dialects, some markedly different from others. The various British dialects also differ in the words that they have borrowed from other languages. Around the middle of the 15th century, there were points where within the 5 major dialects there were almost 500 ways to spell the word though . Following its last major survey of English Dialects (1949–1950),

3827-560: The University of Leeds has started work on a new project. In May 2007 the Arts and Humanities Research Council awarded a grant to Leeds to study British regional dialects. The team are sifting through a large collection of examples of regional slang words and phrases turned up by the "Voices project" run by the BBC , in which they invited the public to send in examples of English still spoken throughout

3916-601: The West Country and other near-by counties of the UK, the consonant R is not pronounced if not followed by a vowel, lengthening the preceding vowel instead. This phenomenon is known as non-rhoticity . In these same areas, a tendency exists to insert an R between a word ending in a vowel and a next word beginning with a vowel. This is called the intrusive R . It could be understood as a merger, in that words that once ended in an R and words that did not are no longer treated differently. This

4005-603: The 21st century. RP, while long established as the standard English accent around the globe due to the spread of the British Empire , is distinct from the standard English pronunciation in some parts of the world; most prominently, RP notably contrasts with standard North American accents. In the 21st century, dictionaries like the Oxford English Dictionary , the Longman Dictionary of Contemporary English ,

4094-816: The English Language (1755) was a large step in the English-language spelling reform , where the purification of language focused on standardising both speech and spelling. By the early 20th century, British authors had produced numerous books intended as guides to English grammar and usage, a few of which achieved sufficient acclaim to have remained in print for long periods and to have been reissued in new editions after some decades. These include, most notably of all, Fowler's Modern English Usage and The Complete Plain Words by Sir Ernest Gowers . Detailed guidance on many aspects of writing British English for publication

4183-644: The Germanic schwein ) is the animal in the field bred by the occupied Anglo-Saxons and pork (like the French porc ) is the animal at the table eaten by the occupying Normans. Another example is the Anglo-Saxon cu meaning cow, and the French bœuf meaning beef. Cohabitation with the Scandinavians resulted in a significant grammatical simplification and lexical enrichment of the Anglo-Frisian core of English;

4272-891: The Oxford Manual is a fairly exhaustive standard for published British English that writers can turn to in the absence of specific guidance from their publishing house. British English is the basis of, and very similar to, Commonwealth English . Commonwealth English is English as spoken and written in the Commonwealth countries , though often with some local variation. This includes English spoken in Australia , Malta , New Zealand , Nigeria , and South Africa . It also includes South Asian English used in South Asia, in English varieties in Southeast Asia , and in parts of Africa. Canadian English

4361-701: The South East, there are significantly different accents; the Cockney accent spoken by some East Londoners is strikingly different from Received Pronunciation (RP). Cockney rhyming slang can be (and was initially intended to be) difficult for outsiders to understand, although the extent of its use is often somewhat exaggerated. Londoners speak with a mixture of accents, depending on ethnicity, neighbourhood, class, age, upbringing, and sundry other factors. Estuary English has been gaining prominence in recent decades: it has some features of RP and some of Cockney. Immigrants to

4450-537: The UK in recent decades have brought many more languages to the country and particularly to London. Surveys started in 1979 by the Inner London Education Authority discovered over 125 languages being spoken domestically by the families of the inner city's schoolchildren. Notably Multicultural London English , a sociolect that emerged in the late 20th century spoken mainly by young, working-class people in multicultural parts of London . Since

4539-621: The United Kingdom , as well as within the countries themselves. The major divisions are normally classified as English English (or English as spoken in England (which is itself broadly grouped into Southern English , West Country , East and West Midlands English and Northern English ), Northern Irish English (in Northern Ireland), Welsh English (not to be confused with the Welsh language ), and Scottish English (not to be confused with

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4628-458: The West Scottish accent. Phonological features characteristic of British English revolve around the pronunciation of the letter R, as well as the dental plosive T and some diphthongs specific to this dialect. Once regarded as a Cockney feature, in a number of forms of spoken British English, /t/ has become commonly realised as a glottal stop [ʔ] when it is in the intervocalic position, in

4717-410: The adjective little is predominant elsewhere. Nevertheless, there is a meaningful degree of uniformity in written English within the United Kingdom, and this could be described by the term British English . The forms of spoken English, however, vary considerably more than in most other areas of the world where English is spoken and so a uniform concept of British English is more difficult to apply to

4806-672: The appearance of resin , chewing gum or (smooth-surfaced) plastic. A principal example is amber , which is a form of fossilized resin. Silky minerals have a parallel arrangement of extremely fine fibres, giving them a lustre reminiscent of silk . Examples include asbestos , ulexite and the satin spar variety of gypsum . A fibrous lustre is similar, but has a coarser texture. Submetallic minerals have similar lustre to metal, but are duller and less reflective. A submetallic lustre often occurs in near-opaque minerals with very high refractive indices, such as sphalerite , cinnabar , anthracite , and cuprite . Vitreous minerals have

4895-481: The award of the grant in 2007, Leeds University stated: that they were "very pleased"—and indeed, "well chuffed"—at receiving their generous grant. He could, of course, have been "bostin" if he had come from the Black Country , or if he was a Scouser he would have been well "made up" over so many spondoolicks, because as a Geordie might say, £460,000 is a "canny load of chink". Most people in Britain speak with

4984-690: The calcite of the shell. The largest documented single crystal of calcite originated from Iceland, measured 7 m × 7 m × 2 m (23 ft × 23 ft × 6.6 ft) and 6 m × 6 m × 3 m (20 ft × 20 ft × 9.8 ft) and weighed about 250 tons. Classic samples have been produced at Madawaska Mine , near Bancroft, Ontario . Bedding parallel veins of fibrous calcite, often referred to in quarrying parlance as beef , occur in dark organic rich mudstones and shales, these veins are formed by increasing fluid pressure during diagenesis . Calcite formation can proceed by several pathways, from

5073-472: The classical terrace ledge kink model to the crystallization of poorly ordered precursor phases like amorphous calcium carbonate (ACC) via an Ostwald ripening process, or via the agglomeration of nanocrystals. The crystallization of ACC can occur in two stages. First, the ACC nanoparticles rapidly dehydrate and crystallize to form individual particles of vaterite . Second, the vaterite transforms to calcite via

5162-613: The country. The BBC Voices project also collected hundreds of news articles about how the British speak English from swearing through to items on language schools. This information will also be collated and analysed by Johnson's team both for content and for where it was reported. "Perhaps the most remarkable finding in the Voices study is that the English language is as diverse as ever, despite our increased mobility and constant exposure to other accents and dialects through TV and radio". When discussing

5251-478: The effect may also occur in other minerals such as aquamarine , moonstone and tourmaline . Colour change is most commonly found in alexandrite, a variety of chrysoberyl gemstones. Other gems also occur in colour-change varieties, including (but not limited to) sapphire , garnet , spinel . Alexandrite displays a colour change dependent upon light, along with strong pleochroism . The gem results from small-scale replacement of aluminium by chromium oxide, which

5340-437: The expansion and eventual collapse of cave systems, resulting in various forms of karst topography . Calcite exhibits an unusual characteristic called retrograde solubility: it is less soluble in water as the temperature increases. Calcite is also more soluble at higher pressures. Pure calcite has the composition CaCO 3 . However, the calcite in limestone often contains a few percent of magnesium . Calcite in limestone

5429-484: The following reaction The carbon dioxide released by this reaction produces a characteristic effervescence when a calcite sample is treated with an acid. Due to its acidity, carbon dioxide has a slight solubilizing effect on calcite. The overall reaction is If the amount of dissolved carbon dioxide drops, the reaction reverses to precipitate calcite. As a result, calcite can be either dissolved by groundwater or precipitated by groundwater, depending on such factors as

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5518-732: The glow curve peaks, it was found that Pb and Mn acted as activators in the calcite lattice, but Pb was much less efficient than Mn . Measuring mineral thermoluminescence experiments usually use x-rays or gamma-rays to activate the sample and record the changes in glowing curves at a temperature of 700–7500 K. Mineral thermoluminescence can form various glow curves of crystals under different conditions, such as temperature changes, because impurity ions or other crystal defects present in minerals supply luminescence centers and trapping levels. Observing these curve changes also can help infer geological correlation and age determination. Calcite, like most carbonates, dissolves in acids by

5607-453: The idea of two different morphemes, one that causes the double negation, and one that is used for the point or the verb. Standard English in the United Kingdom, as in other English-speaking nations, is widely enforced in schools and by social norms for formal contexts but not by any singular authority; for instance, there is no institution equivalent to the Académie française with French or

5696-511: The last southern Midlands accent to use the broad "a" in words like bath or grass (i.e. barth or grarss ). Conversely crass or plastic use a slender "a". A few miles northwest in Leicestershire the slender "a" becomes more widespread generally. In the town of Corby , five miles (8 km) north, one can find Corbyite which, unlike the Kettering accent, is largely influenced by

5785-508: The later Norman occupation led to the grafting onto that Germanic core of a more elaborate layer of words from the Romance branch of the European languages. This Norman influence entered English largely through the courts and government. Thus, English developed into a "borrowing" language of great flexibility and with a huge vocabulary . Dialects and accents vary amongst the four countries of

5874-437: The lustre of glass . (The term is derived from the Latin for glass, vitrum .) This type of lustre is one of the most commonly seen, and occurs in transparent or translucent minerals with relatively low refractive indices. Common examples include calcite , quartz , topaz , beryl , tourmaline and fluorite , among others. Waxy minerals have a lustre resembling wax . Examples include jade and chalcedony . Asterism

5963-452: The mass internal migration to Northamptonshire in the 1940s and given its position between several major accent regions, it has become a source of various accent developments. In Northampton the older accent has been influenced by overspill Londoners. There is an accent known locally as the Kettering accent, which is a transitional accent between the East Midlands and East Anglian . It is

6052-510: The material's body colour. In aventurine quartz , chrome-bearing fuchsite makes for a green stone and various iron oxides make for a red stone. Chatoyant minerals display luminous bands, which appear to move as the specimen is rotated. Such minerals are composed of parallel fibers (or contain fibrous voids or inclusions), which reflect light into a direction perpendicular to their orientation, thus forming narrow bands of light. The most famous examples are tiger's eye and cymophane , but

6141-458: The modern period, but due to their remoteness from the Germanic languages , influence on English was notably limited . However, the degree of influence remains debated, and it has recently been argued that its grammatical influence accounts for the substantial innovations noted between English and the other West Germanic languages. Initially, Old English was a diverse group of dialects, reflecting

6230-427: The ocean at the time they became mineralised, and retained this mineralogy for the remainder of their evolutionary history. Petrographic evidence for these calcite sea conditions consists of calcitic ooids , lmc cements, hardgrounds , and rapid early seafloor aragonite dissolution. The evolution of marine organisms with calcium carbonate shells may have been affected by the calcite and aragonite sea cycle. Calcite

6319-514: The primary inorganic precipitate of calcium carbonate in marine waters was low-magnesium calcite (lmc), as opposed to the aragonite and high-magnesium calcite (hmc) precipitated today. Calcite seas alternated with aragonite seas over the Phanerozoic , being most prominent in the Ordovician and Jurassic periods. Lineages evolved to use whichever morph of calcium carbonate was favourable in

6408-446: The rhombohedron form. Its fracture is conchoidal , but difficult to obtain. Scalenohedral faces are chiral and come in pairs with mirror-image symmetry; their growth can be influenced by interaction with chiral biomolecules such as L- and D- amino acids . Rhombohedral faces are not chiral. Calcite is transparent to opaque and may occasionally show phosphorescence or fluorescence . A transparent variety called " Iceland spar "

6497-433: The sky through the crystal and then rotating it so that the two images are of equal brightness, the rings of polarized light that surround the sun can be seen even under overcast skies. Identifying the sun's location would give seafarers a reference point for navigating on their lengthy sea voyages. In World War II, high-grade optical calcite was used for gun sights, specifically in bomb sights and anti-aircraft weaponry. It

6586-401: The spoken language. Globally, countries that are former British colonies or members of the Commonwealth tend to follow British English, as is the case for English used by European Union institutions. In China, both British English and American English are taught. The UK government actively teaches and promotes English around the world and operates in over 200 countries . English is

6675-549: The subsurface in response to microorganism activity, such as sulfate -dependent anaerobic oxidation of methane , where methane is oxidized and sulfate is reduced , leading to precipitation of calcite and pyrite from the produced bicarbonate and sulfide . These processes can be traced by the specific carbon isotope composition of the calcites, which are extremely depleted in the C isotope, by as much as −125 per mil PDB (δ C). Calcite seas existed in Earth's history when

6764-503: The surface of a stone that occurs when light is reflected between layers of minerals. It is seen in moonstone and labradorite and is very similar to adularescence and aventurescence . British English British English (abbreviations: BrE , en-GB , and BE ) is the set of varieties of the English language native to the United Kingdom of Great Britain and Northern Ireland . More narrowly, it can refer specifically to

6853-417: The term alabaster because of the close association. Many other cultures have used the material for similar carved objects and applications. A transparent variety of calcite known as Iceland spar may have been used by Vikings for navigating on cloudy days. A very pure crystal of calcite can split a beam of sunlight into dual images, as the polarized light deviates slightly from the main beam. By observing

6942-414: The term vitreous (derived from the Latin for glass , vitrum ) refers to a glassy lustre. A list of these terms is given below. Lustre varies over a wide continuum, and so there are no rigid boundaries between the different types of lustre. (For this reason, different sources can often describe the same mineral differently. This ambiguity is further complicated by lustre's ability to vary widely within

7031-587: The theft of work tools worth £500 from a van at the Sprucefield park and ride car park in Lisburn. A football team can be treated likewise: Arsenal have lost just one of 20 home Premier League matches against Manchester City. This tendency can be observed in texts produced already in the 19th century. For example, Jane Austen , a British author, writes in Chapter 4 of Pride and Prejudice , published in 1813: All

7120-403: The traditional accent of Newcastle upon Tyne , 'out' will sound as 'oot', and in parts of Scotland and North-West England, 'my' will be pronounced as 'me'. Long vowels /iː/ and /uː/ are diphthongised to [ɪi] and [ʊu] respectively (or, more technically, [ʏʉ], with a raised tongue), so that ee and oo in feed and food are pronounced with a movement. The diphthong [oʊ] is also pronounced with

7209-457: The type of weathering the substrate experienced: growth on physically weathered surfaces has a shingled morphology due to Volmer-Weber growth, growth on chemically weathered surfaces has characteristics of Stranski-Krastanov growth, and growth on pristine cleavage surfaces has characteristics of Frank - van der Merwe growth. These differences are apparently due to the influence of surface roughness on layer coalescence dynamics. Calcite may form in

7298-733: The varied origins of the Anglo-Saxon kingdoms of England. One of these dialects, Late West Saxon , eventually came to dominate. The original Old English was then influenced by two waves of invasion: the first was by speakers of the Scandinavian branch of the Germanic family, who settled in parts of Britain in the eighth and ninth centuries; the second was the Normans in the 11th century, who spoke Old Norman and ultimately developed an English variety of this called Anglo-Norman . These two invasions caused English to become "mixed" to some degree (though it

7387-495: The water temperature, pH , and dissolved ion concentrations. When conditions are right for precipitation, calcite forms mineral coatings that cement rock grains together and can fill fractures. When conditions are right for dissolution, the removal of calcite can dramatically increase the porosity and permeability of the rock, and if it continues for a long period of time, may result in the formation of caves . Continued dissolution of calcium carbonate-rich formations can lead to

7476-402: The word 'British' and as a result can be used and interpreted in two ways, more broadly or more narrowly, within a range of blurring and ambiguity". Variations exist in formal (both written and spoken) English in the United Kingdom. For example, the adjective wee is almost exclusively used in parts of Scotland, north-east England, Northern Ireland, Ireland, and occasionally Yorkshire , whereas

7565-560: The world are good and agreeable in your eyes. However, in Chapter 16, the grammatical number is used. The world is blinded by his fortune and consequence. Some dialects of British English use negative concords, also known as double negatives . Rather than changing a word or using a positive, words like nobody, not, nothing, and never would be used in the same sentence. While this does not occur in Standard English, it does occur in non-standard dialects. The double negation follows

7654-405: The {1 0 1} or {1 0 4} directions (the most common cleavage plane). Habits include acute to obtuse rhombohedra, tabular habits, prisms , or various scalenohedra . Calcite exhibits several twinning types that add to the observed habits. It may occur as fibrous, granular, lamellar, or compact. A fibrous, efflorescent habit is known as lublinite . Cleavage is usually in three directions parallel to

7743-426: Was conducted by adding activators such as ions of Mn, Fe, Co, Ni, Cu, Zn, Ag, Pb, and Bi to the calcite samples to observe whether they emitted heat or light. The results showed that adding ions ( Cu , Cu , Zn , Ag , Bi , Fe , Fe , Co , Ni ) did not react. However, a reaction occurred when both manganese and lead ions were present in calcite. By changing the temperature and observing

7832-422: Was never a truly mixed language in the strictest sense of the word; mixed languages arise from the cohabitation of speakers of different languages, who develop a hybrid tongue for basic communication). The more idiomatic, concrete and descriptive English is, the more it is from Anglo-Saxon origins. The more intellectual and abstract English is, the more it contains Latin and French influences, e.g. swine (like

7921-455: Was used as a polarizer (in Nicol prisms ) before the invention of Polaroid plates and still finds use in optical instruments. Also, experiments have been conducted to use calcite for a cloak of invisibility . Microbiologically precipitated calcite has a wide range of applications, such as soil remediation, soil stabilization and concrete repair. It also can be used for tailings management and

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