Misplaced Pages

#661338

83-457: Millerite is a common metamorphic mineral replacing pentlandite within serpentinite ultramafics . It is formed in this way by removal of sulfur from pentlandite or other nickeliferous sulfide minerals during metamorphism or metasomatism . Millerite is also formed from sulfur poor olivine cumulates by nucleation. Millerite is thought to form from sulfur and nickel which exist in pristine olivine in trace amounts, and which are driven out of

166-700: A ρ w 1 − ρ a ρ w = R D V − ρ a ρ w 1 − ρ a ρ w . {\displaystyle RD_{\mathrm {A} }={{\rho _{\mathrm {s} } \over \rho _{\mathrm {w} }}-{\rho _{\mathrm {a} } \over \rho _{\mathrm {w} }} \over 1-{\rho _{\mathrm {a} } \over \rho _{\mathrm {w} }}}={RD_{\mathrm {V} }-{\rho _{\mathrm {a} } \over \rho _{\mathrm {w} }} \over 1-{\rho _{\mathrm {a} } \over \rho _{\mathrm {w} }}}.} In

249-465: A ) . {\displaystyle F_{\mathrm {w} }=g\left(m_{\mathrm {b} }-\rho _{\mathrm {a} }{\frac {m_{\mathrm {b} }}{\rho _{\mathrm {b} }}}+V\rho _{\mathrm {w} }-V\rho _{\mathrm {a} }\right).} If we subtract the force measured on the empty bottle from this (or tare the balance before making the water measurement) we obtain. F w , n = g V ( ρ w − ρ

332-445: A ) = ρ s − ρ a ρ w − ρ a . {\displaystyle SG_{\mathrm {A} }={\frac {gV(\rho _{\mathrm {s} }-\rho _{\mathrm {a} })}{gV(\rho _{\mathrm {w} }-\rho _{\mathrm {a} })}}={\frac {\rho _{\mathrm {s} }-\rho _{\mathrm {a} }}{\rho _{\mathrm {w} }-\rho _{\mathrm {a} }}}.} This

415-418: A ) , {\displaystyle F_{\mathrm {s,n} }=gV(\rho _{\mathrm {s} }-\rho _{\mathrm {a} }),} where ρ s is the density of the sample. The ratio of the sample and water forces is: S G A = g V ( ρ s − ρ a ) g V ( ρ w − ρ

498-439: A ) , {\displaystyle F_{\mathrm {w,n} }=gV(\rho _{\mathrm {w} }-\rho _{\mathrm {a} }),} where the subscript n indicated that this force is net of the force of the empty bottle. The bottle is now emptied, thoroughly dried and refilled with the sample. The force, net of the empty bottle, is now: F s , n = g V ( ρ s − ρ

581-405: A m p l e {\displaystyle \rho _{\mathrm {sample} }} is the density of the sample and ρ H 2 O {\displaystyle \rho _{\mathrm {H_{2}O} }} is the density of water. The apparent specific gravity is simply the ratio of the weights of equal volumes of sample and water in air: S G a p p

664-670: A m p l e V m H 2 O V = m s a m p l e m H 2 O g g = W V , sample W V , H 2 O , {\displaystyle SG_{\mathrm {true} }={\frac {\rho _{\mathrm {sample} }}{\rho _{\mathrm {H_{2}O} }}}={\frac {\frac {m_{\mathrm {sample} }}{V}}{\frac {m_{\mathrm {H_{2}O} }}{V}}}={\frac {m_{\mathrm {sample} }}{m_{\mathrm {H_{2}O} }}}{\frac {g}{g}}={\frac {W_{\mathrm {V} ,{\text{sample}}}}{W_{\mathrm {V} ,\mathrm {H_{2}O} }}},} where g

747-405: A r e n t = W A , sample W A , H 2 O , {\displaystyle SG_{\mathrm {apparent} }={\frac {W_{\mathrm {A} ,{\text{sample}}}}{W_{\mathrm {A} ,\mathrm {H_{2}O} }}},} where W A , sample {\displaystyle W_{A,{\text{sample}}}} represents the weight of

830-472: A given reference material. Specific gravity for solids and liquids is nearly always measured with respect to water at its densest (at 4 °C or 39.2 °F); for gases, the reference is air at room temperature (20 °C or 68 °F). The term "relative density" (abbreviated r.d. or RD ) is preferred in SI , whereas the term "specific gravity" is gradually being abandoned. If a substance's relative density

913-464: A grade equal to, or higher than, greenschist facies will cause solid massive sulfides to deform in a ductile fashion and to travel some distance into the country rock and along structures. Upon cessation of metamorphism, the sulfides may inherit a foliated or sheared texture, and typically develop bright, equigranular to globular aggregates of porphyroblastic pentlandite crystals known colloquially as "fish scales". Metamorphism may also alter

SECTION 10

#1732848842662

996-462: A large meteorite impact crater. The pentlandite-chalcopyrite-pyrrhotite ore around the Sudbury Structure formed from sulfide melts that segregated from the melt sheet produced by the impact. Specific gravity Relative density , also called specific gravity , is a dimensionless quantity defined as the ratio of the density (mass of a unit volume) of a substance to the density of

1079-411: A liquid can be measured using a hydrometer. This consists of a bulb attached to a stalk of constant cross-sectional area, as shown in the adjacent diagram. First the hydrometer is floated in the reference liquid (shown in light blue), and the displacement (the level of the liquid on the stalk) is marked (blue line). The reference could be any liquid, but in practice it is usually water. The hydrometer

1162-461: A metallic luster. For this reason, the best way to discern pentlandite is by its paler color, lack of magnetism, and light brownish bronze streak. In contrast, pyrite , pyrrhotite and chalcopyrite will all display much darker streaks: brownish black, greyish black, greenish black respectively. When looked at using reflected light ore microscopy, it possesses key diagnostic properties such as octahedral cleavage , and its alteration to bravoite,

1245-412: A molar volume of 22.259 L under those same conditions. Those with SG greater than 1 are denser than water and will, disregarding surface tension effects, sink in it. Those with an SG less than 1 are less dense than water and will float on it. In scientific work, the relationship of mass to volume is usually expressed directly in terms of the density (mass per unit volume) of the substance under study. It

1328-560: A pinkish to brownish violet sulfide mineral that occurs in euhedral to octahedral crystals. Pentlandite usually develops as granular inclusions within other sulfide minerals (mainly pyrrhotite), often taking the shape of thin veins or "flames". Although pentlandite is an opaque mineral, it exhibits a strong light creamy reflectance . Pentlandite occurs alongside sulfide minerals such as bravoite, chalcopyrite, cubanite , millerite , pyrrhotite, valleriite , as well as other minerals like chromite , ilmenite , magnetite , and sperrylite . It

1411-413: A relative density of about 0.91, will float. A substance with a relative density greater than 1 will sink. Temperature and pressure must be specified for both the sample and the reference. Pressure is nearly always 1 atm (101.325 kPa ). Where it is not, it is more usual to specify the density directly. Temperatures for both sample and reference vary from industry to industry. In British brewing practice,

1494-462: A specific, but not necessarily accurately known volume, V and is placed upon a balance, it will exert a force F b = g ( m b − ρ a m b ρ b ) , {\displaystyle F_{\mathrm {b} }=g\left(m_{\mathrm {b} }-\rho _{\mathrm {a} }{\frac {m_{\mathrm {b} }}{\rho _{\mathrm {b} }}}\right),} where m b

1577-429: Is a dimensionless quantity , as it is the ratio of either densities or weights R D = ρ s u b s t a n c e ρ r e f e r e n c e , {\displaystyle {\mathit {RD}}={\frac {\rho _{\mathrm {substance} }}{\rho _{\mathrm {reference} }}},} where R D {\displaystyle RD}

1660-409: Is a device used to determine the density of a liquid. A pycnometer is usually made of glass , with a close-fitting ground glass stopper with a capillary tube through it, so that air bubbles may escape from the apparatus. This device enables a liquid's density to be measured accurately by reference to an appropriate working fluid, such as water or mercury , using an analytical balance . If

1743-664: Is an accessory mineral associated with nickel laterite deposits in New Caledonia . Millerite is found as a metamorphic replacement of pentlandite within the Silver Swan nickel deposit, Western Australia, and throughout the many ultramafic serpentinite bodies of the Yilgarn Craton , Western Australia , generally as a replacement of metamorphosed pentlandite. There is one known occurrence of millerite in South Africa, near Pafuri in

SECTION 20

#1732848842662

1826-420: Is being measured. For true ( in vacuo ) relative density calculations air pressure must be considered (see below). Temperatures are specified by the notation ( T s / T r ) with T s representing the temperature at which the sample's density was determined and T r the temperature at which the reference (water) density is specified. For example, SG (20 °C/4 °C) would be understood to mean that

1909-422: Is being measured. For true ( in vacuo ) specific gravity calculations, air pressure must be considered (see below). Temperatures are specified by the notation ( T s / T r ), with T s representing the temperature at which the sample's density was determined and T r the temperature at which the reference (water) density is specified. For example, SG (20 °C/4 °C) would be understood to mean that

1992-408: Is called the apparent relative density , denoted by subscript A, because it is what we would obtain if we took the ratio of net weighings in air from an analytical balance or used a hydrometer (the stem displaces air). Note that the result does not depend on the calibration of the balance. The only requirement on it is that it read linearly with force. Nor does RD A depend on the actual volume of

2075-473: Is chemically similar to mackinawite , godlevskite and horomanite. Pentlandite is synonymous with folgerite, horbachite, lillhammerite, and nicopyrite. The pentlandite group is a subdivision of rare minerals that share similar chemical and structural properties with pentlandite, hence the name. Their chemical formula can be written as XY 8 ( S , Se ) 8 in which X is usually replaced by silver , manganese , cadmium , and lead , while copper takes

2158-422: Is easy to measure, the volume of an irregularly shaped sample can be more difficult to ascertain. One method is to put the sample in a water-filled graduated cylinder and read off how much water it displaces. Alternatively the container can be filled to the brim, the sample immersed, and the volume of overflow measured. The surface tension of the water may keep a significant amount of water from overflowing, which

2241-786: Is especially problematic for small samples. For this reason it is desirable to use a water container with as small a mouth as possible. For each substance, the density, ρ , is given by ρ = Mass Volume = Deflection × Spring Constant Gravity Displacement W a t e r L i n e × Area C y l i n d e r . {\displaystyle \rho ={\frac {\text{Mass}}{\text{Volume}}}={\frac {{\text{Deflection}}\times {\frac {\text{Spring Constant}}{\text{Gravity}}}}{{\text{Displacement}}_{\mathrm {WaterLine} }\times {\text{Area}}_{\mathrm {Cylinder} }}}.} When these densities are divided, references to

2324-469: Is extremely important that the analyst enter the table with the correct form of relative density. For example, in the brewing industry, the Plato table , which lists sucrose concentration by mass against true RD, were originally (20 °C/4 °C) that is based on measurements of the density of sucrose solutions made at laboratory temperature (20 °C) but referenced to the density of water at 4 °C which

2407-417: Is extremely important that the analyst enter the table with the correct form of specific gravity. For example, in the brewing industry, the Plato table lists sucrose concentration by weight against true SG, and was originally (20 °C/4 °C) i.e. based on measurements of the density of sucrose solutions made at laboratory temperature (20 °C) but referenced to the density of water at 4 °C which

2490-501: Is filled with air but as that air displaces an equal amount of air the weight of that air is canceled by the weight of the air displaced. Now we fill the bottle with the reference fluid e.g. pure water. The force exerted on the pan of the balance becomes: F w = g ( m b − ρ a m b ρ b + V ρ w − V ρ

2573-762: Is formed. This phase is called monosulfide solid solution (MSS), and is unstable at low temperatures decomposing to mixtures of pentlandite and pyrrhotite , and (rarely) pyrite . It is only upon cooling past ~550 °C (1,022 °F) (dependent on composition) that the MSS undergoes exsolution . A separate phase, usually a copper-rich sulfide liquid may also form, giving rise to chalcopyrite upon cooling. These phases typically form aphanitic equigranular massive sulfides, or are present as disseminated sulfides within rocks composed mostly of silicates. Pristine magmatic massive sulfide are rarely preserved as most deposits of nickeliferous sulfide have been metamorphosed. Metamorphism at

Millerite - Misplaced Pages Continue

2656-458: Is found in abundance within ultramafic rocks, making it one of the most important sources of mined nickel. It also occasionally occurs within mantle xenoliths and "black smoker" hydrothermal vents . It is named after Irish scientist Joseph Barclay Pentland (1797–1873), who first noted the mineral at Sudbury, Ontario. In the field, pentlandite is often confused with other sulfide minerals, as they are all brassy yellowish in color and have

2739-487: Is in industry where specific gravity finds wide application, often for historical reasons. True specific gravity of a liquid can be expressed mathematically as: S G t r u e = ρ s a m p l e ρ H 2 O , {\displaystyle SG_{\mathrm {true} }={\frac {\rho _{\mathrm {sample} }}{\rho _{\mathrm {H_{2}O} }}},} where ρ s

2822-408: Is less than 1 then it is less dense than the reference; if greater than 1 then it is denser than the reference. If the relative density is exactly 1 then the densities are equal; that is, equal volumes of the two substances have the same mass. If the reference material is water, then a substance with a relative density (or specific gravity) less than 1 will float in water. For example, an ice cube, with

2905-607: Is more easily and perhaps more accurately measured without measuring volume. Using a spring scale, the sample is weighed first in air and then in water. Relative density (with respect to water) can then be calculated using the following formula: R D = W a i r W a i r − W w a t e r , {\displaystyle RD={\frac {W_{\mathrm {air} }}{W_{\mathrm {air} }-W_{\mathrm {water} }}},} where This technique cannot easily be used to measure relative densities less than one, because

2988-515: Is necessary to specify the temperatures and pressures at which the densities or masses were determined. It is nearly always the case that measurements are made at nominally 1 atmosphere (101.325 kPa ignoring the variations caused by changing weather patterns) but as relative density usually refers to highly incompressible aqueous solutions or other incompressible substances (such as petroleum products) variations in density caused by pressure are usually neglected at least where apparent relative density

3071-437: Is normally assumed to be water at 4 ° C (or, more precisely, 3.98 °C, which is the temperature at which water reaches its maximum density). In SI units, the density of water is (approximately) 1000  kg / m or 1  g / cm , which makes relative density calculations particularly convenient: the density of the object only needs to be divided by 1000 or 1, depending on the units. The relative density of gases

3154-623: Is often measured with respect to dry air at a temperature of 20 °C and a pressure of 101.325 kPa absolute, which has a density of 1.205 kg/m . Relative density with respect to air can be obtained by R D = ρ g a s ρ a i r ≈ M g a s M a i r , {\displaystyle {\mathit {RD}}={\frac {\rho _{\mathrm {gas} }}{\rho _{\mathrm {air} }}}\approx {\frac {M_{\mathrm {gas} }}{M_{\mathrm {air} }}},} where M {\displaystyle M}

3237-425: Is produced, the propensity for this mineral to resorb sulfur, and for the sulfur to be removed via the concomitant loss of volatiles from the serpentinite, tends to lower sulfur fugacity . This forms disseminated needle like millerite crystals dispersed throughout the rock mass. Millerite may be associated with heazlewoodite and is considered a transitional stage in the metamorphic production of heazlewoodite via

3320-520: Is quite rare in specimen form, and the most common source of the mineral is in the Halls Gap area of Lincoln County, Kentucky in the United States . Pentlandite Pentlandite is an iron – nickel sulfide with the chemical formula ( Fe , Ni ) 9 S 8 . Pentlandite has a narrow variation range in nickel to iron ratios (Ni:Fe), but it is usually described as 1:1. In some cases, this ratio

3403-455: Is relative density, ρ s u b s t a n c e {\displaystyle \rho _{\mathrm {substance} }} is the density of the substance being measured, and ρ r e f e r e n c e {\displaystyle \rho _{\mathrm {reference} }} is the density of the reference. (By convention ρ {\displaystyle \rho } ,

Millerite - Misplaced Pages Continue

3486-404: Is skewed by the presence of pyrrhotite inclusions . It also contains minor cobalt , usually at low levels as a fraction of weight. Pentlandite forms isometric crystals, but it is normally found in massive granular aggregates . It is brittle with a hardness of 3.5–4 and specific gravity of 4.6–5.0 and is non-magnetic. It has a yellowish bronze color and a metallic luster . Pentlandite

3569-499: Is taken from this work which uses SG (17.5 °C/17.5 °C). As a final example, the British RD units are based on reference and sample temperatures of 60 °F and are thus (15.56 °C/15.56 °C). Relative density can be calculated directly by measuring the density of a sample and dividing it by the (known) density of the reference substance. The density of the sample is simply its mass divided by its volume. Although mass

3652-403: Is the molar mass and the approximately equal sign is used because equality pertains only if 1 mol of the gas and 1 mol of air occupy the same volume at a given temperature and pressure, i.e., they are both ideal gases . Ideal behaviour is usually only seen at very low pressure. For example, one mol of an ideal gas occupies 22.414 L at 0 °C and 1 atmosphere whereas carbon dioxide has

3735-511: Is the local acceleration due to gravity, V is the volume of the sample and of water (the same for both), ρ sample is the density of the sample, ρ H 2 O is the density of water, W V represents a weight obtained in vacuum, m s a m p l e {\displaystyle {\mathit {m}}_{\mathrm {sample} }} is the mass of the sample and m H 2 O {\displaystyle {\mathit {m}}_{\mathrm {H_{2}O} }}

3818-606: Is the mass of an equal volume of water. The density of water and of the sample varies with temperature and pressure, so it is necessary to specify the temperatures and pressures at which the densities or weights were determined. Measurements are nearly always made at 1 nominal atmosphere (101.325 kPa ± variations from changing weather patterns), but as specific gravity usually refers to highly incompressible aqueous solutions or other incompressible substances (such as petroleum products), variations in density caused by pressure are usually neglected at least where apparent specific gravity

3901-422: Is the mass of the bottle and g the gravitational acceleration at the location at which the measurements are being made. ρ a is the density of the air at the ambient pressure and ρ b is the density of the material of which the bottle is made (usually glass) so that the second term is the mass of air displaced by the glass of the bottle whose weight, by Archimedes Principle must be subtracted. The bottle

3984-412: Is then filled with a liquid of known density, in which the powder is completely insoluble. The weight of the displaced liquid can then be determined, and hence the relative density of the powder. A gas pycnometer , the gas-based manifestation of a pycnometer, compares the change in pressure caused by a measured change in a closed volume containing a reference (usually a steel sphere of known volume) with

4067-432: Is then floated in a liquid of unknown density (shown in green). The change in displacement, Δ x , is noted. In the example depicted, the hydrometer has dropped slightly in the green liquid; hence its density is lower than that of the reference liquid. It is necessary that the hydrometer floats in both liquids. The application of simple physical principles allows the relative density of the unknown liquid to be calculated from

4150-595: Is very close to the temperature at which water has its maximum density of ρ ( H 2 O ) equal to 0.999972 g/cm (or 62.43 lb·ft ). The ASBC table in use today in North America, while it is derived from the original Plato table is for apparent relative density measurements at (20 °C/20 °C) on the IPTS-68 scale where the density of water is 0.9982071 g/cm . In the sugar, soft drink, honey, fruit juice and related industries sucrose concentration by mass

4233-512: Is very close to the temperature at which water has its maximum density, ρ H 2 O equal to 999.972 kg/m in SI units ( 0.999 972  g/cm in cgs units or 62.43 lb/cu ft in United States customary units ). The ASBC table in use today in North America for apparent specific gravity measurements at (20 °C/20 °C) is derived from the original Plato table using Plato et al.‘s value for SG(20 °C/4 °C) = 0.998 2343 . In

SECTION 50

#1732848842662

4316-491: The Archimedes buoyancy principle, the buoyancy force acting on the hydrometer is equal to the weight of liquid displaced. This weight is equal to the mass of liquid displaced multiplied by g , which in the case of the reference liquid is ρ ref Vg . Setting these equal, we have m g = ρ r e f V g {\displaystyle mg=\rho _{\mathrm {ref} }Vg} or just Exactly

4399-512: The Transvaal. The deposit has never been commercially mined. It is commonly found as radiating clusters of acicular needle-like crystals in cavities in sulfide rich limestone and dolomite or in geodes . It is also found in nickel-iron meteorites , such as CK carbonaceous chondrites . Millerite was discovered by Wilhelm Haidinger in 1845 in the coal mines of Wales . It was named for British mineralogist William Hallowes Miller . The mineral

4482-461: The mineral content of a rock or other sample. Gemologists use it as an aid in the identification of gemstones . Water is preferred as the reference because measurements are then easy to carry out in the field (see below for examples of measurement methods). As the principal use of relative density measurements in industry is determination of the concentrations of substances in aqueous solutions and these are found in tables of RD vs concentration it

4565-474: The Greek letter rho , denotes density.) The reference material can be indicated using subscripts: R D s u b s t a n c e / r e f e r e n c e {\displaystyle RD_{\mathrm {substance/reference} }} which means "the relative density of substance with respect to reference ". If the reference is not explicitly stated then it

4648-508: The above formula: ρ s u b s t a n c e = S G × ρ H 2 O . {\displaystyle \rho _{\mathrm {substance} }=SG\times \rho _{\mathrm {H_{2}O} }.} Occasionally a reference substance other than water is specified (for example, air), in which case specific gravity means density relative to that reference. The density of substances varies with temperature and pressure so that it

4731-487: The above process. Millerite, when found in enough concentration, is a very important ore of nickel because, for its mass as a sulfide mineral, it contains a higher percentage of nickel than pentlandite . This means that, for every percent of millerite, an ore contains more nickel than an equivalent percentage of pentlandite sulfide. Millerite forms an important ore constituent of the Silver Swan, Wannaway, Cliffs, Honeymoon Well, Yakabindie and Mt Keith (MKD5) orebodies. It

4814-405: The change in displacement. (In practice the stalk of the hydrometer is pre-marked with graduations to facilitate this measurement.) In the explanation that follows, Since the floating hydrometer is in static equilibrium , the downward gravitational force acting upon it must exactly balance the upward buoyancy force. The gravitational force acting on the hydrometer is simply its weight, mg . From

4897-411: The change in pressure caused by the sample under the same conditions. The difference in change of pressure represents the volume of the sample as compared to the reference sphere, and is usually used for solid particulates that may dissolve in the liquid medium of the pycnometer design described above, or for porous materials into which the liquid would not fully penetrate. When a pycnometer is filled to

4980-447: The concentration of nickel and the Ni:Fe ratio and Ni:S ratio of the sulfides. In this case, pentlandite may be replaced by millerite , and rarely heazlewoodite . Metamorphism may also be associated with metasomatism , and it is particularly common for arsenic to react with pre-existing sulfides, producing nickeline , gersdorffite and other Ni–Co arsenides. Pentlandite is found within

5063-487: The densities used here and in the rest of this article are based on that scale. On the previous IPTS-68 scale, the densities at 20 °C and 4 °C are 0.998 2041 and 0.999 9720 respectively, resulting in an SG (20 °C/4 °C) value for water of 0.998 232 . As the principal use of specific gravity measurements in industry is determination of the concentrations of substances in aqueous solutions and as these are found in tables of SG versus concentration, it

SECTION 60

#1732848842662

5146-406: The densities used here and in the rest of this article are based on that scale. On the previous IPTS-68 scale the densities at 20 °C and 4 °C are, respectively, 0.9982041 and 0.9999720 resulting in an RD (20 °C/4 °C) value for water of 0.99823205. The temperatures of the two materials may be explicitly stated in the density symbols; for example: where the superscript indicates

5229-410: The density of dry air at 101.325 kPa at 20 °C is 0.001205 g/cm and that of water is 0.998203 g/cm we see that the difference between true and apparent relative densities for a substance with relative density (20 °C/20 °C) of about 1.100 would be 0.000120. Where the relative density of the sample is close to that of water (for example dilute ethanol solutions) the correction

5312-407: The density of the sample was determined at 20 °C and of the water at 4 °C. Taking into account different sample and reference temperatures, while SG H 2 O = 1.000 000 (20 °C/20 °C), it is also the case that SG H 2 O = 0.998 2008 ⁄ 0.999 9720 = 0.998 2288 (20 °C/4 °C). Here, temperature is being specified using the current ITS-90 scale and

5395-399: The density of the sample was determined at 20 °C and of the water at 4 °C. Taking into account different sample and reference temperatures, while SG H 2 O = 1.000000 (20 °C/20 °C) it is also the case that RD H 2 O = ⁠ 0.9982008 / 0.9999720 ⁠ = 0.9982288 (20 °C/4 °C). Here temperature is being specified using the current ITS-90 scale and

5478-412: The flask is weighed empty, full of water, and full of a liquid whose relative density is desired, the relative density of the liquid can easily be calculated. The particle density of a powder, to which the usual method of weighing cannot be applied, can also be determined with a pycnometer. The powder is added to the pycnometer, which is then weighed, giving the weight of the powder sample. The pycnometer

5561-439: The formation of nickel-bearing sulfides is essentially restricted to sulfide saturated mafic and ultramafic melts. Minor amounts of nickel sulfides are found in mantle peridotites . The behaviour of sulfide melts is complex and is affected by copper, nickel, iron, and sulfur ratios. Typically, above 1100 °C, only one sulfide melt exists. Upon cooling to 1000 °C, a solid containing mostly Fe and minor amounts of Ni and Cu

5644-702: The lower margins of mineralized layered intrusions , the best examples being the Bushveld igneous complex , South Africa , the Voisey's Bay troctolite intrusive complex in Canada , the Duluth gabbro , in North America, and various other localities throughout the world. In these locations, pentlandite is considered an important nickel ore. Pentlandite is also the dominant ore mineral occurring in Kambalda type komatiitic nickel ore deposits ,

5727-428: The most common being olivine , as well as nickeliferous varieties of amphibole , biotite , pyroxene and spinel . Nickel substitutes most readily for Fe and Co because or their similarity in size and charge. In sulfide saturated melts, nickel behaves as a chalcophile element and partitions strongly into the sulfide phase. Because most nickel behaves as a compatible element in igneous differentiation processes,

5810-477: The olivine during metamorphic processes. Magmatic olivine generally has up to ~4000 ppm Ni and up to 2500 ppm S within the crystal lattice , as contaminants and substituting for other transition metals with similar ionic radii (Fe and Mn). During metamorphism, sulfur and nickel within the olivine lattice are reconstituted into metamorphic sulfide minerals, chiefly millerite, during serpentinization and talc carbonate alteration. When metamorphic olivine

5893-549: The place of Y . Iron, nickel, and cobalt have the ability to occupy both X or Y positions. These minerals are: Pentlandite is the most common terrestrial nickel sulfide. It typically forms during cooling of a sulfide melt. These sulfide melts, in turn, are typically formed during the evolution of a silicate melt. Because nickel is a chalcophile element, it has preference for (i.e. it "partitions into") sulfide phases. In sulfide undersaturated melts, nickel substitutes for other transition metals within ferromagnesian minerals,

5976-508: The prime example of which can be found in the Yilgarn Craton of Western Australia . Similar deposits exist at Nkomati, Namibia , in the Thompson Belt , Canada, and a few examples from Brazil. Pentlandite, but primarily chalcopyrite and PGEs , are also obtained from the supergiant Norilsk nickel deposit, in trans-Siberian Russia. The Sudbury Basin in Ontario , Canada, is associated with

6059-438: The pycnometer. Further manipulation and finally substitution of RD V , the true relative density (the subscript V is used because this is often referred to as the relative density in vacuo ), for ρ s / ρ w gives the relationship between apparent and true relative density: R D A = ρ s ρ w − ρ

6142-766: The reference liquid, and the known properties of the hydrometer. If Δ x is small then, as a first-order approximation of the geometric series equation ( 4 ) can be written as: R D n e w / r e f ≈ 1 + A Δ x m ρ r e f . {\displaystyle RD_{\mathrm {new/ref} }\approx 1+{\frac {A\Delta x}{m}}\rho _{\mathrm {ref} }.} This shows that, for small Δ x , changes in displacement are approximately proportional to changes in relative density. A pycnometer (from Ancient Greek : πυκνός , romanized :  puknos , lit.   'dense'), also called pyknometer or specific gravity bottle ,

6225-417: The same equation applies when the hydrometer is floating in the liquid being measured, except that the new volume is V − A Δ x (see note above about the sign of Δ x ). Thus, Combining ( 1 ) and ( 2 ) yields But from ( 1 ) we have V = m / ρ ref . Substituting into ( 3 ) gives This equation allows the relative density to be calculated from the change in displacement, the known density of

6308-500: The sample measured in air and W A , H 2 O {\displaystyle {W_{\mathrm {A} ,\mathrm {H_{2}O} }}} the weight of an equal volume of water measured in air. It can be shown that true specific gravity can be computed from different properties: S G t r u e = ρ s a m p l e ρ H 2 O = m s

6391-405: The sample will then float. W water becomes a negative quantity, representing the force needed to keep the sample underwater. Another practical method uses three measurements. The sample is weighed dry. Then a container filled to the brim with water is weighed, and weighed again with the sample immersed, after the displaced water has overflowed and been removed. Subtracting the last reading from

6474-459: The specific gravity, as specified above, is multiplied by 1000. Specific gravity is commonly used in industry as a simple means of obtaining information about the concentration of solutions of various materials such as brines , must weight ( syrups , juices, honeys, brewers wort , must , etc.) and acids. Relative density ( R D {\displaystyle RD} ) or specific gravity ( S G {\displaystyle SG} )

6557-1256: The spring constant, gravity and cross-sectional area simply cancel, leaving R D = ρ o b j e c t ρ r e f = Deflection O b j . Displacement O b j . Deflection R e f . Displacement R e f . = 3   i n 20   m m 5   i n 34   m m = 3   i n × 34   m m 5   i n × 20   m m = 1.02. {\displaystyle RD={\frac {\rho _{\mathrm {object} }}{\rho _{\mathrm {ref} }}}={\frac {\frac {{\text{Deflection}}_{\mathrm {Obj.} }}{{\text{Displacement}}_{\mathrm {Obj.} }}}{\frac {{\text{Deflection}}_{\mathrm {Ref.} }}{{\text{Displacement}}_{\mathrm {Ref.} }}}}={\frac {\frac {3\ \mathrm {in} }{20\ \mathrm {mm} }}{\frac {5\ \mathrm {in} }{34\ \mathrm {mm} }}}={\frac {3\ \mathrm {in} \times 34\ \mathrm {mm} }{5\ \mathrm {in} \times 20\ \mathrm {mm} }}=1.02.} Relative density

6640-481: The sugar, soft drink, honey, fruit juice and related industries, sucrose concentration by weight is taken from a table prepared by A. Brix , which uses SG (17.5 °C/17.5 °C). As a final example, the British SG units are based on reference and sample temperatures of 60 °F and are thus (15.56 °C/15.56 °C). Given the specific gravity of a substance, its actual density can be calculated by rearranging

6723-418: The sum of the first two readings gives the weight of the displaced water. The relative density result is the dry sample weight divided by that of the displaced water. This method allows the use of scales which cannot handle a suspended sample. A sample less dense than water can also be handled, but it has to be held down, and the error introduced by the fixing material must be considered. The relative density of

6806-426: The temperature at which the density of the material is measured, and the subscript indicates the temperature of the reference substance to which it is compared. Relative density can also help to quantify the buoyancy of a substance in a fluid or gas, or determine the density of an unknown substance from the known density of another. Relative density is often used by geologists and mineralogists to help determine

6889-453: The usual case we will have measured weights and want the true relative density. This is found from R D V = R D A − ρ a ρ w ( R D A − 1 ) . {\displaystyle RD_{\mathrm {V} }=RD_{\mathrm {A} }-{\rho _{\mathrm {a} } \over \rho _{\mathrm {w} }}(RD_{\mathrm {A} }-1).} Since

#661338