77-719: The Badu Building is located in the City of Llano , Llano County, Texas . It was added to the National Register of Historic Places listings in Llano County, Texas in 1980, and designated a Recorded Texas Historic Landmark in 1981. It has also been known as the Badu House and as the Carol Phelan Building. It is now being operated as a restaurant and private event space under the name Badu 1891. Designed by Larramour and Watson,
154-453: A live oak on the south bank of the river, near the present site of Roy Inks Bridge in Llano. Into the 1870s, the town was little more than a frontier trading center, with a few log buildings housing business establishments, a post office , and a few homes. In 1879, the first bank, Moore, Foster, and Company, was founded, and during the 1880s, Llano acquired a number of new enterprises that served
231-585: A bend in the middle that is caused by start of the twin. Penetration twins consist of two single crystals that have grown into each other; examples of this twinning include cross-shaped staurolite twins and Carlsbad twinning in orthoclase. Cyclic twins are caused by repeated twinning around a rotation axis. This type of twinning occurs around three, four, five, six, or eight-fold axes, and the corresponding patterns are called threelings, fourlings, fivelings , sixlings, and eightlings. Sixlings are common in aragonite. Polysynthetic twins are similar to cyclic twins through
308-417: A bigger coordination numbers because of the increase in relative size as compared to oxygen (the last orbital subshell of heavier atoms is different too). Changes in coordination numbers leads to physical and mineralogical differences; for example, at high pressure, such as in the mantle , many minerals, especially silicates such as olivine and garnet , will change to a perovskite structure , where silicon
385-416: A definite crystalline structure, such as opal or obsidian , are more properly called mineraloids . If a chemical compound occurs naturally with different crystal structures, each structure is considered a different mineral species. Thus, for example, quartz and stishovite are two different minerals consisting of the same compound, silicon dioxide . The International Mineralogical Association (IMA)
462-470: A distinct mineral: The details of these rules are somewhat controversial. For instance, there have been several recent proposals to classify amorphous substances as minerals, but they have not been accepted by the IMA. The IMA is also reluctant to accept minerals that occur naturally only in the form of nanoparticles a few hundred atoms across, but has not defined a minimum crystal size. Some authors require
539-603: A former mayor, was built after a flood crest of 42 feet in 1935 swept away the 1892 structure. By 1964, the town had a new hospital, a post office, school buildings, a community center, a rodeo area, and a golf course, along with a city park and improved water system. Llano was an important link in the Highland Lakes chain of tourist areas, and attracted many hunters during the deer season. A winery, feed processing, and insecticide and commercial talc production represented new industry. Actress Sophia Loren , friend and correspondent of
616-463: A key to defining a substance as a mineral. A 2011 article defined icosahedrite , an aluminium-iron-copper alloy, as a mineral; named for its unique natural icosahedral symmetry , it is a quasicrystal . Unlike a true crystal, quasicrystals are ordered but not periodic. A rock is an aggregate of one or more minerals or mineraloids. Some rocks, such as limestone or quartzite , are composed primarily of one mineral – calcite or aragonite in
693-409: A mineral defines how much it can resist scratching or indentation. This physical property is controlled by the chemical composition and crystalline structure of a mineral. The most commonly used scale of measurement is the ordinal Mohs hardness scale, which measures resistance to scratching. Defined by ten indicators, a mineral with a higher index scratches those below it. The scale ranges from talc,
770-833: A restaurant. N. J. Badu was a native of Nancy, France . Educated and trained as a geologist in Europe, Badu emigrated from France to Mexico. From there, he traveled to New Orleans , eventually finding employment in Texas as an instructor of the French language , in the Lamar County town of Paris . He married a woman from the same county by the name of Charlie Neal. After a subsequent career change, he gained some experience at hotel management in Dallas and Austin . During his tenure in Paris, Badu had heard much about
847-432: A sedimentary mineral, and silicic acid ): Under low-grade metamorphic conditions, kaolinite reacts with quartz to form pyrophyllite (Al 2 Si 4 O 10 (OH) 2 ): As metamorphic grade increases, the pyrophyllite reacts to form kyanite and quartz: Alternatively, a mineral may change its crystal structure as a consequence of changes in temperature and pressure without reacting. For example, quartz will change into
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#1733092339634924-406: A tetrahedral fashion; on the other hand, graphite is composed of sheets of carbons in sp hybrid orbitals, where each carbon is bonded covalently to only three others. These sheets are held together by much weaker van der Waals forces , and this discrepancy translates to large macroscopic differences. Twinning is the intergrowth of two or more crystals of a single mineral species. The geometry of
1001-935: A variety of its SiO 2 polymorphs , such as tridymite and cristobalite at high temperatures, and coesite at high pressures. Classifying minerals ranges from simple to difficult. A mineral can be identified by several physical properties, some of them being sufficient for full identification without equivocation. In other cases, minerals can only be classified by more complex optical , chemical or X-ray diffraction analysis; these methods, however, can be costly and time-consuming. Physical properties applied for classification include crystal structure and habit, hardness, lustre, diaphaneity, colour, streak, cleavage and fracture, and specific gravity. Other less general tests include fluorescence , phosphorescence , magnetism , radioactivity , tenacity (response to mechanical induced changes of shape or form), piezoelectricity and reactivity to dilute acids . Crystal structure results from
1078-498: A variety of minerals because of the need to balance charges. Because the eight most common elements make up over 98% of the Earth's crust, the small quantities of the other elements that are typically present are substituted into the common rock-forming minerals. The distinctive minerals of most elements are quite rare, being found only where these elements have been concentrated by geological processes, such as hydrothermal circulation , to
1155-595: A white mica, can be used for windows (sometimes referred to as isinglass), as a filler, or as an insulator. Ores are minerals that have a high concentration of a certain element, typically a metal. Examples are cinnabar (HgS), an ore of mercury; sphalerite (ZnS), an ore of zinc; cassiterite (SnO 2 ), an ore of tin; and colemanite , an ore of boron . Gems are minerals with an ornamental value, and are distinguished from non-gems by their beauty, durability, and usually, rarity. There are about 20 mineral species that qualify as gem minerals, which constitute about 35 of
1232-560: Is a city in Llano County, Texas , United States. As of 2020 , the city population was 3,325. It is the county seat of Llano County. Llano has been described as the " deer capital of Texas", with the single highest density of white-tailed deer in the United States. Llano County was established in compliance with a February 1, 1856, state legislative act. The Llano River location was chosen in an election held on June 14, 1856, under
1309-429: Is a purple variety of the mineral species quartz . Some mineral species can have variable proportions of two or more chemical elements that occupy equivalent positions in the mineral's structure; for example, the formula of mackinawite is given as (Fe,Ni) 9 S 8 , meaning Fe x Ni 9- x S 8 , where x is a variable number between 0 and 9. Sometimes a mineral with variable composition
1386-707: Is a sedimentary rock composed primarily of organically derived carbon. In rocks, some mineral species and groups are much more abundant than others; these are termed the rock-forming minerals. The major examples of these are quartz, the feldspars , the micas , the amphiboles , the pyroxenes , the olivines , and calcite; except for the last one, all of these minerals are silicates. Overall, around 150 minerals are considered particularly important, whether in terms of their abundance or aesthetic value in terms of collecting. Commercially valuable minerals and rocks, other than gemstones, metal ores, or mineral fuels, are referred to as industrial minerals . For example, muscovite ,
1463-664: Is currently a part of District 1-AAA, also including Blanco, Comfort, Ingram Moore, Brady and Florence. Llano is widely known as the Deer Capital of Texas, though its effort to be officially designated as such was rejected in 2016. The density of white-tailed deer in the Llano Basin is the highest in the nation. Hunters from all over come to Llano for deer, quail , dove , feral pig , and turkey hunting, using guns or bows. The bald eagle makes its home in Llano County during its annual winter migration with most birds found around
1540-445: Is in octahedral coordination. Other examples are the aluminosilicates kyanite , andalusite , and sillimanite (polymorphs, since they share the formula Al 2 SiO 5 ), which differ by the coordination number of the Al ; these minerals transition from one another as a response to changes in pressure and temperature. In the case of silicate materials, the substitution of Si by Al allows for
1617-599: Is located on the Llano River , 65 miles (105 km) northwest of Austin and 102 mi (164 km) north of San Antonio . According to the United States Census Bureau , the city has a total area of 4.7 sq mi (12 km ), of which 0.3 sq mi (0.78 km ) of it (5.53%) is covered by water. In October 2018, Llano experienced heavy rainfall and flooding following Hurricane Sergio . Rainfall in Llano exceeded 9.8 inches (250 mm) and
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#17330923396341694-408: Is possible for one element to be substituted for another. Chemical substitution will occur between ions of a similar size and charge; for example, K will not substitute for Si because of chemical and structural incompatibilities caused by a big difference in size and charge. A common example of chemical substitution is that of Si by Al , which are close in charge, size, and abundance in the crust. In
1771-470: Is possible for two rocks to have an identical or a very similar bulk rock chemistry without having a similar mineralogy. This process of mineralogical alteration is related to the rock cycle . An example of a series of mineral reactions is illustrated as follows. Orthoclase feldspar (KAlSi 3 O 8 ) is a mineral commonly found in granite , a plutonic igneous rock . When exposed to weathering, it reacts to form kaolinite (Al 2 Si 2 O 5 (OH) 4 ,
1848-653: Is split into separate species, more or less arbitrarily, forming a mineral group ; that is the case of the silicates Ca x Mg y Fe 2- x - y SiO 4 , the olivine group . Besides the essential chemical composition and crystal structure, the description of a mineral species usually includes its common physical properties such as habit , hardness , lustre , diaphaneity , colour, streak , tenacity , cleavage , fracture , parting, specific gravity , magnetism , fluorescence , radioactivity , as well as its taste or smell and its reaction to acid . Minerals are classified by key chemical constituents;
1925-524: Is the angle opposite the a-axis, viz. the angle between the b and c axes): The hexagonal crystal family is also split into two crystal systems – the trigonal , which has a three-fold axis of symmetry, and the hexagonal, which has a six-fold axis of symmetry. Chemistry and crystal structure together define a mineral. With a restriction to 32 point groups, minerals of different chemistry may have identical crystal structure. For example, halite (NaCl), galena (PbS), and periclase (MgO) all belong to
2002-422: Is the generally recognized standard body for the definition and nomenclature of mineral species. As of November 2024 , the IMA recognizes 6,100 official mineral species. The chemical composition of a named mineral species may vary somewhat due to the inclusion of small amounts of impurities. Specific varieties of a species sometimes have conventional or official names of their own. For example, amethyst
2079-405: Is the hardest natural substance, has an adamantine lustre, and belongs to the isometric crystal family, whereas graphite is very soft, has a greasy lustre, and crystallises in the hexagonal family. This difference is accounted for by differences in bonding. In diamond, the carbons are in sp hybrid orbitals, which means they form a framework where each carbon is covalently bonded to four neighbours in
2156-456: Is typical of garnet, prismatic (elongated in one direction), and tabular, which differs from bladed habit in that the former is platy whereas the latter has a defined elongation. Related to crystal form, the quality of crystal faces is diagnostic of some minerals, especially with a petrographic microscope. Euhedral crystals have a defined external shape, while anhedral crystals do not; those intermediate forms are termed subhedral. The hardness of
2233-572: The 2020 United States census , 3,325 people, 1,221 households, and 809 families were residing in the city. As of the census of 2000, 3,325 people, 1,353 households, and 880 families resided in the city. The population density was 748.1 inhabitants per square mile (288.8/km ). The 1,539 housing units averaged 346.3/sq mi (133.8/km ) in density. The racial makeup of the city was 94.35% White, 0.57% African American, 0.66% Native American, 0.24% Asian, 3.40% from other races, and 0.78% from two or more races. Hispanics or Latinos of any race were 8.90% of
2310-488: The American West , worked on the staff for a brief time early in the 20th century. Anticipation of significant economic growth based on the iron deposits discovered at Iron Mountain in northwestern Llano County attracted capital from Dallas and from northern states, and the boom years of Llano-from 1886 to 1893-were launched. The Llano Improvement and Furnace Company undertook plans for an iron furnace and foundry , and
2387-614: The CIPW norm , which gives reasonable estimates for volcanic rock formed from dry magma. The chemical composition may vary between end member species of a solid solution series. For example, the plagioclase feldspars comprise a continuous series from sodium -rich end member albite (NaAlSi 3 O 8 ) to calcium -rich anorthite (CaAl 2 Si 2 O 8 ) with four recognized intermediate varieties between them (given in order from sodium- to calcium-rich): oligoclase , andesine , labradorite , and bytownite . Other examples of series include
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2464-504: The Lake Buchanan area. Llanite , a rare type of brown rhyolite porphyry with sky-blue quartz crystals and rusty-pink microcline feldspar , is found nowhere else in the world except in Llano County. Llanite can be found along a highway cut 9 mi (14 km) north of Llano on Texas 16. The largest piece of polished llanite in the world can be seen at the Badu House. The centuries-long habitation of various Native American tribes in
2541-700: The Netherlands native Anthony Goossens, priest of Holy Trinity Catholic Church in Llano, contributed to the church fund-raising campaign in 1975. By 1983, the National Register of Historic Places listed, in addition to the courthouse, the Llano jail, the Southern Hotel, and the Badu Building, former bank and home of French immigrant and mineralogist N. J. Badu, now a bed-and-breakfast establishment. In 2021 County Judge Ron Cunningham removed books, such as In
2618-496: The hydrosphere , atmosphere , and biosphere . The group's scope includes mineral-forming microorganisms, which exist on nearly every rock, soil, and particle surface spanning the globe to depths of at least 1600 metres below the sea floor and 70 kilometres into the stratosphere (possibly entering the mesosphere ). Biogeochemical cycles have contributed to the formation of minerals for billions of years. Microorganisms can precipitate metals from solution , contributing to
2695-798: The 1880s the Llano Rural , the town's first newspaper , was established, followed by the Iron City News , the name of which reflects growing interest in the county's mineral resources. The Rural eventually incorporated several other newspapers, including the Advocate , the Searchlight , and the Gazette , to become the Llano News by the early 1900s. The Llano Times was where J. Marvin Hunter , author and historian of
2772-451: The 78 mineral classes listed in the Dana classification scheme. Skinner's (2005) definition of a mineral takes this matter into account by stating that a mineral can be crystalline or amorphous. Although biominerals are not the most common form of minerals, they help to define the limits of what constitutes a mineral proper. Nickel's (1995) formal definition explicitly mentioned crystallinity as
2849-507: The Badu Building was erected in 1890 by the Llano Improvement and Furnace Company, as the location of the newly chartered First National Bank. The building is constructed of local granite and locally manufactured red brick. The marble-floored street level with its carved wooden interiors were the public access portion of the bank. The second floor was designed for office space. The Llano Improvement and Furnace Company had been organized with
2926-431: The IMA's decision to exclude biogenic crystalline substances. For example, Lowenstam (1981) stated that "organisms are capable of forming a diverse array of minerals, some of which cannot be formed inorganically in the biosphere." Skinner (2005) views all solids as potential minerals and includes biominerals in the mineral kingdom, which are those that are created by the metabolic activities of organisms. Skinner expanded
3003-455: The IMA. They are most commonly named after a person , followed by discovery location; names based on chemical composition or physical properties are the two other major groups of mineral name etymologies. Most names end in "-ite"; the exceptions are usually names that were well-established before the organization of mineralogy as a discipline, for example galena and diamond . A topic of contention among geologists and mineralogists has been
3080-548: The Latin species , "a particular sort, kind, or type with distinct look, or appearance". The abundance and diversity of minerals is controlled directly by their chemistry, in turn dependent on elemental abundances in the Earth. The majority of minerals observed are derived from the Earth's crust . Eight elements account for most of the key components of minerals, due to their abundance in the crust. These eight elements, summing to over 98% of
3157-524: The Night Kitchen , from the shelves of the main library because they contained nudity. He also ordered librarians to pause buying new material and to purge any other books containing nudity. County commissioners dissolved the library board in 2022. The replacement board voted unanimously to close its meetings to the public to prevent observers from taking notes on the meetings. It removed more books, including Caste: The Origins of Our Discontents . Llano
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3234-536: The West", but only a small dam and the street lighting were completed. By one report, the population reached 7,000 in 1890. In 1892, at the peak of the boom period, the town was incorporated, the river was bridged, and the Austin and Northwestern Railroad was extended to a terminal on the north side of Llano. Because of the improved transportation, several granite-cutting and -finishing businesses moved to town in this period. Many of
3311-488: The aluminium abundance is unusually high, the excess aluminium will form muscovite or other aluminium-rich minerals. If silicon is deficient, part of the feldspar will be replaced by feldspathoid minerals. Precise predictions of which minerals will be present in a rock of a particular composition formed at a particular temperature and pressure requires complex thermodynamic calculations. However, approximate estimates may be made using relatively simple rules of thumb , such as
3388-546: The area has produced numerous archaeological sites which attract amateur archaeologists year-round. Mineral In geology and mineralogy , a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form. The geological definition of mineral normally excludes compounds that occur only in living organisms. However, some minerals are often biogenic (such as calcite ) or organic compounds in
3465-470: The boom period soon faded. Plans to connect Llano with Fredericksburg via an extension of the San Antonio and Aransas Pass Railway were not fulfilled. A series of fires in the early 1890s, probably set to collect insurance on unprofitable properties, destroyed many of the new business establishments. Such fires were so numerous, fire insurance was denied to the town for several years. Farming, ranching, and
3542-449: The bulk chemistry of the parent body. For example, in most igneous rocks, the aluminium and alkali metals (sodium and potassium) that are present are primarily found in combination with oxygen, silicon, and calcium as feldspar minerals. However, if the rock is unusually rich in alkali metals, there will not be enough aluminium to combine with all the sodium as feldspar, and the excess sodium will form sodic amphiboles such as riebeckite . If
3619-424: The case of limestone, and quartz in the latter case. Other rocks can be defined by relative abundances of key (essential) minerals; a granite is defined by proportions of quartz, alkali feldspar , and plagioclase feldspar . The other minerals in the rock are termed accessory minerals , and do not greatly affect the bulk composition of the rock. Rocks can also be composed entirely of non-mineral material; coal
3696-630: The city was $ 16,306. About 7.7% of families and 10.2% of the population were below the poverty line , including 13.8% of those under age 18 and 2.6% of those age 65 or over. The City of Llano is served by the Llano Independent School District , which includes Packsaddle Elementary, Llano Elementary, Llano Junior High, and Llano High School. Llano's mascot is the Yellow Jacket and the school colors are orange and black. The Llano Independent School District serves about 1,900 students, and
3773-465: The city, the age distribution was 24.5% under 18, 7.2% from 18 to 24, 23.9% from 25 to 44, 22.4% from 45 to 64, and 22.0% who were 65 or older. The median age was 41 years. For every 100 females, there were 89.9 males. For every 100 females age 18 and over, there were 83.1 males. The median income for a household in the city was $ 31,706, and for a family was $ 38,125. Males had a median income of $ 29,464 versus $ 19,958 for females. The per capita income for
3850-415: The coordination of the silicate is by a number: in the case of the silica tetrahedron, the silicon is said to have a coordination number of 4. Various cations have a specific range of possible coordination numbers; for silicon, it is almost always 4, except for very high-pressure minerals where the compound is compressed such that silicon is in six-fold (octahedral) coordination with oxygen. Bigger cations have
3927-422: The county's farmers and ranchers . After the county outgrew the one-story stone building that had housed its public offices, in 1885, an ornate brick courthouse was completed on the square on the south side of the river. A fire on January 22, 1892, destroyed this courthouse; the present county courthouse was completed and occupied on August 1, 1893. It is listed in the National Register of Historic Places . In
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#17330923396344004-417: The crust by weight, are, in order of decreasing abundance: oxygen , silicon , aluminium , iron , magnesium , calcium , sodium and potassium . Oxygen and silicon are by far the two most important – oxygen composes 47% of the crust by weight, and silicon accounts for 28%. The minerals that form are those that are most stable at the temperature and pressure of formation, within the limits imposed by
4081-404: The development of commercial real estate , on the hitherto undeveloped north side of the river. Charters were undertaken for a dam , an electric power plant , a streetcar system, and electric street lights , while expectations of growth were high. Steel -town names such as Birmingham , Pittsburgh , and Bessemer were chosen for streets on the north side; Llano was to be the "Pittsburgh of
4158-434: The difference in charge has to accounted for by making a second substitution of Si by Al . Coordination polyhedra are geometric representations of how a cation is surrounded by an anion. In mineralogy, coordination polyhedra are usually considered in terms of oxygen, due its abundance in the crust. The base unit of silicate minerals is the silica tetrahedron – one Si surrounded by four O . An alternate way of describing
4235-414: The dipyramidal point group. These differences arise corresponding to how aluminium is coordinated within the crystal structure. In all minerals, one aluminium ion is always in six-fold coordination with oxygen. Silicon, as a general rule, is in four-fold coordination in all minerals; an exception is a case like stishovite (SiO 2 , an ultra-high pressure quartz polymorph with rutile structure). In kyanite,
4312-517: The example of plagioclase, there are three cases of substitution. Feldspars are all framework silicates, which have a silicon-oxygen ratio of 2:1, and the space for other elements is given by the substitution of Si by Al to give a base unit of [AlSi 3 O 8 ] ; without the substitution, the formula would be charge-balanced as SiO 2 , giving quartz. The significance of this structural property will be explained further by coordination polyhedra. The second substitution occurs between Na and Ca ; however,
4389-745: The formation of ore deposits. They can also catalyze the dissolution of minerals. Prior to the International Mineralogical Association's listing, over 60 biominerals had been discovered, named, and published. These minerals (a sub-set tabulated in Lowenstam (1981) ) are considered minerals proper according to Skinner's (2005) definition. These biominerals are not listed in the International Mineral Association official list of mineral names; however, many of these biomineral representatives are distributed amongst
4466-410: The generic AX 2 formula; these two groups are collectively known as the pyrite and marcasite groups. Polymorphism can extend beyond pure symmetry content. The aluminosilicates are a group of three minerals – kyanite , andalusite , and sillimanite – which share the chemical formula Al 2 SiO 5 . Kyanite is triclinic, while andalusite and sillimanite are both orthorhombic and belong to
4543-688: The geology of Llano. He was hired by the Llano Improvement and Furnace Company to manage the Algona Hotel, the area's grand upscale establishment. When the Llano Improvement and Furnace Company went bankrupt, the Algona closed. Badu became employed as a manager of the Driskill Hotel in Austin, but maintained his home in Llano. Badu became a full-time mineralogist, with his laboratory based in Llano. Llano, Texas Llano ( / ˈ l æ n oʊ / LAN -oh )
4620-406: The granite industry remained the foundations of the town's economy in the 20th century. In the 1920s, Llano was a major shipping point for cattle; the cotton industry flourished in the county through the 1930s, but declined thereafter into insignificance. Granite quarrying and finishing retained their importance, amounting to a million-dollar-a-year industry by the 1950s. The Roy Inks Bridge, named for
4697-451: The hexaoctahedral point group (isometric family), as they have a similar stoichiometry between their different constituent elements. In contrast, polymorphs are groupings of minerals that share a chemical formula but have a different structure. For example, pyrite and marcasite , both iron sulfides, have the formula FeS 2 ; however, the former is isometric while the latter is orthorhombic. This polymorphism extends to other sulfides with
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#17330923396344774-462: The level of Llano River rose about 30 feet (9.1 m) in 12 hours. The body of an unidentified woman was found on the banks alongside the Colorado River following the flooding in Llano. Llano experiences a humid subtropical climate, with hot summers and generally mild winters. Temperature averages range from 84 °F (29 °C) in the summer to 46 °F (7.8 °C) during winter. As of
4851-461: The material to be a stable or metastable solid at room temperature (25 °C). However, the IMA only requires that the substance be stable enough for its structure and composition to be well-determined. For example, it has recently recognized meridianiite (a naturally occurring hydrate of magnesium sulfate ) as a mineral, even though it is formed and stable only below 2 °C. As of November 2024 , 6,100 mineral species are approved by
4928-489: The most common gemstones. Gem minerals are often present in several varieties, and so one mineral can account for several different gemstones; for example, ruby and sapphire are both corundum , Al 2 O 3 . The first known use of the word "mineral" in the English language ( Middle English ) was the 15th century. The word came from Medieval Latin : minerale , from minera , mine, ore. The word "species" comes from
5005-428: The most encompassing of these being the six crystal families. These families can be described by the relative lengths of the three crystallographic axes, and the angles between them; these relationships correspond to the symmetry operations that define the narrower point groups. They are summarized below; a, b, and c represent the axes, and α, β, γ represent the angle opposite the respective crystallographic axis (e.g. α
5082-457: The new businesses were begun in the boom period, and substantial brick establishments were constructed around the public square on the north side of the river. Among these, the Algona Hotel became a focal point for the town's new social life. It was damaged by a cyclone in 1900, and burned to the ground in 1923. Because the county's mineral resources, with the significant exception of granite, did not exist in commercially exploitable concentrations,
5159-402: The olivine series of magnesium-rich forsterite and iron-rich fayalite, and the wolframite series of manganese -rich hübnerite and iron-rich ferberite . Chemical substitution and coordination polyhedra explain this common feature of minerals. In nature, minerals are not pure substances, and are contaminated by whatever other elements are present in the given chemical system. As a result, it
5236-622: The orderly geometric spatial arrangement of atoms in the internal structure of a mineral. This crystal structure is based on regular internal atomic or ionic arrangement that is often expressed in the geometric form that the crystal takes. Even when the mineral grains are too small to see or are irregularly shaped, the underlying crystal structure is always periodic and can be determined by X-ray diffraction. Minerals are typically described by their symmetry content. Crystals are restricted to 32 point groups , which differ by their symmetry. These groups are classified in turn into more broad categories,
5313-563: The point where they can no longer be accommodated in common minerals. Changes in temperature and pressure and composition alter the mineralogy of a rock sample. Changes in composition can be caused by processes such as weathering or metasomatism ( hydrothermal alteration ). Changes in temperature and pressure occur when the host rock undergoes tectonic or magmatic movement into differing physical regimes. Changes in thermodynamic conditions make it favourable for mineral assemblages to react with each other to produce new minerals; as such, it
5390-412: The population. Of the 1,353 households, 28.8% had children under 18 living with them, 48.6% were married couples living together, 12.9% had a female householder with no husband present, and 34.9% were not families. About 31.3% of all households were made up of individuals, and 18.2% had someone living alone who was 65 or older. The average household size was 2.35, and the average family size was 2.95. In
5467-447: The presence of repetitive twinning; however, instead of occurring around a rotational axis, polysynthetic twinning occurs along parallel planes, usually on a microscopic scale. Crystal habit refers to the overall shape of crystal. Several terms are used to describe this property. Common habits include acicular, which describes needlelike crystals as in natrolite , bladed, dendritic (tree-pattern, common in native copper ), equant, which
5544-560: The previous definition of a mineral to classify "element or compound, amorphous or crystalline, formed through biogeochemical processes," as a mineral. Recent advances in high-resolution genetics and X-ray absorption spectroscopy are providing revelations on the biogeochemical relations between microorganisms and minerals that may shed new light on this question. For example, the IMA-commissioned "Working Group on Environmental Mineralogy and Geochemistry " deals with minerals in
5621-485: The second aluminium is in six-fold coordination; its chemical formula can be expressed as Al Al SiO 5 , to reflect its crystal structure. Andalusite has the second aluminium in five-fold coordination (Al Al SiO 5 ) and sillimanite has it in four-fold coordination (Al Al SiO 5 ). Differences in crystal structure and chemistry greatly influence other physical properties of the mineral. The carbon allotropes diamond and graphite have vastly different properties; diamond
5698-505: The sense of chemistry (such as mellite ). Moreover, living organisms often synthesize inorganic minerals (such as hydroxylapatite ) that also occur in rocks. The concept of mineral is distinct from rock , which is any bulk solid geologic material that is relatively homogeneous at a large enough scale. A rock may consist of one type of mineral or may be an aggregate of two or more different types of minerals, spacially segregated into distinct phases . Some natural solid substances without
5775-470: The specific purpose of promoting land development in the area, but went bankrupt circa 1894. The building was sold to N. J. Badu in 1898 at a public auction. Until 1980, the building had been continuously owned by members of Badu's family. From 1907 to 1912, the building was leased to the First State Bank of Llano. The Badu family sold it in 1980. It has been used as a bed and breakfast facility, and as
5852-439: The twinning is controlled by the mineral's symmetry. As a result, there are several types of twins, including contact twins, reticulated twins, geniculated twins, penetration twins, cyclic twins, and polysynthetic twins. Contact, or simple twins, consist of two crystals joined at a plane; this type of twinning is common in spinel. Reticulated twins, common in rutile, are interlocking crystals resembling netting. Geniculated twins have
5929-468: The two dominant systems are the Dana classification and the Strunz classification. Silicate minerals comprise approximately 90% of the Earth's crust . Other important mineral groups include the native elements , sulfides , oxides , halides , carbonates , sulfates , and phosphates . The International Mineralogical Association has established the following requirements for a substance to be considered
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