Bultfonteinite | |
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General | |
Category | Nesosilicates |
Formula (repeating unit) | Ca2SiO2(OH,F)4 |
IMA symbol | Bul [1] |
Strunz classification | 9.AG.80 [2] |
Dana classification | 52.4.7.2 [2] |
Crystal system | Triclinic |
Crystal class | Pinacoidal (1) (same H-M symbol) |
Space group | P1 |
Unit cell | a = 10.99 Å, b = 8.18 Å c = 5.67 Å, α = 93.95° β = 91.32°, γ = 89.85°; [2] Z = 4 |
Identification | |
Color | Colorless, pink |
Twinning | Interpenetrating on {100} and {010}; polysynthetic |
Cleavage | Good on {100} and {010} |
Fracture | Conchoidal |
Mohs scale hardness | 4.5 |
Luster | Vitreous |
Streak | White [2] |
Diaphaneity | Transparent |
Optical properties | Biaxial (+) |
Refractive index | nα = 1.587 nβ = 1.590 nγ = 1.597 [2] |
Birefringence | δ = 0.010 [2] |
2V angle | 70° (measured) |
Dispersion | r > v; barely perceptible |
Solubility | Soluble in hydrochloric acid [3] |
References | [4] |
Bultfonteinite, originally dutoitspanite, is a pink to colorless mineral with chemical formula Ca2SiO2(OH,F)4. It was discovered in 1903 or 1904 in the Bultfontein mine in South Africa, for which the mineral is named, and described in 1932.
Bultfonteinite is transparent and pale pink to colorless. The mineral occurs as radiating prismatic acicular crystals and radial spherules up to 2 cm (0.79 in). [4]
The crystal structure of bultfonteinite consists of strips of [Ca4Si2O4]8+, that run along the 5.67 Å c-axis, held together by Ca–O–Ca, Ca–F–Ca, Ca–H2O–Ca, and Ca–O–Si bonds. Silicon atoms occur in isolated tetrahedra and the calcium atoms have seven-fold coordination, derived from a triangular prism with a seventh atom present on one of the square faces. [5]
In either 1903 or 1904, a miner discovered the first specimen of bultfonteinite on the 480-foot level of the Bultfontein mine in Kimberley, South Africa. The mineral occurred in a several-hundred-foot-tall horse of kimberlite-enclosed dolerite and shale fragments. The specimen, mistakenly thought to be natrolite, was given to Alpheus F. Williams. Several years later, additional samples were found by C. E. Adams in the nearby Dutoitspan mine and given to the MacGregor Museum in Kimberley. [6] Shortly before 1932, the mineral was found about 100 miles (160 km) to the southeast of Kimberley at the Jagersfontein Mine in Orange River Colony. [6] [7]
After John Parry and F. E. Wright described the mineral afwillite in 1925, Williams recognized that his samples of bultfonteinite were not natrolite, but were likely a new mineral species. Chemical analysis by John Parry and crystallographic and optical determination by Wright proved it to be a new mineral. [8] The mineral was described by Parry, Williams, and Wright in 1932 and named bultfonteinite. [6] Their original description does not explicitly state the origin of the name, but it is presumably named after the mine in which it was discovered. [3] Earlier that year in his book The Genesis of the Diamond, Williams had called the mineral dutoitspanite, a name which was "apparently discarded". [7] [9] When the International Mineralogical Association was founded, bultfonteinite was grandfathered as a valid mineral species. [2]
The type material is held in England at Cambridge University and the Natural History Museum in London. [4]
Bultfonteinite has been found in Australia, Botswana, Canada, Israel, Japan, Jordan, Russia, South Africa, and the United States. [2] The mineral was first located outside South Africa in the US State of California in 1955. [7] Bultfonteinite has been found in association with afwillite, apophyllite, calcite, natrolite, oyelite, scawtite, and xonotlite. [4]
At the type locality, the mineral occurred in a large structure of dolerite and shale fragments in a kimberlite pipe. [6] In Crestmore, California, bultfonteinite formed in the contact zone of thermally metamorphosed limestone. [4]
Uvarovite is a chromium-bearing garnet group species with the formula: Ca3Cr2(SiO4)3. It was discovered in 1832 by Germain Henri Hess who named it after Count Sergei Semenovitch Uvarov (1765–1855), a Russian statesman and amateur mineral collector. It is classified in the ugrandite group alongside the other calcium-bearing garnets andradite and grossular.
Natrolite is a tectosilicate mineral species belonging to the zeolite group. It is a hydrated sodium and aluminium silicate with the formula Na2Al2Si3O10 · 2H2O. The type locality is Hohentwiel, Hegau, Germany.
Afwillite is a calcium hydroxide nesosilicate mineral with formula Ca3(SiO3OH)2·2H2O. It occurs as glassy, colorless to white prismatic monoclinic crystals. Its Mohs scale hardness is between 3 and 4. It occurs as an alteration mineral in contact metamorphism of limestone. It occurs in association with apophyllite, natrolite, thaumasite, merwinite, spurrite, gehlenite, ettringite, portlandite, hillebrandite, foshagite, brucite and calcite.
Xonotlite, or eakleite, is a mineral of general formula Ca6Si6O17(OH)2 named by the German mineralogist Karl Friedrich August Rammelsberg in 1866. The name originates from its discovery locality, Tetela de Xonotla, Puebla, Mexico. Although it was discovered in 1866, it was first described in 1959. It is approved by the IMA, but it is a grandfathered species, meaning the name supposedly represents a valid species til this day.
Aliettite is a complex phyllosilicate mineral of the smectite group with a formula of (Ca0.2Mg6(Si,Al)8O20(OH)4·4H2O) or [Mg3Si4O10(OH)2](Ca0.5,Na)0.33(Al,Mg,Fe2+)2-3(Si,Al)4O10(OH)2·n(H2O).
Edingtonite is a white, gray, brown, colorless, pink or yellow zeolite mineral. Its chemical formula is BaAl2Si3O10·4H2O. It has varieties with tetragonal, orthorhombic or triclinic crystals.
Huttonite is a thorium nesosilicate mineral with the chemical formula ThSiO4 and which crystallizes in the monoclinic system. It is dimorphous with tetragonal thorite, and isostructual with monazite. An uncommon mineral, huttonite forms transparent or translucent cream–colored crystals. It was first identified in samples of beach sands from the West Coast region of New Zealand by the mineralogist Colin Osborne Hutton (1910–1971). Owing to its rarity, huttonite is not an industrially useful mineral.
Jennite is a calcium silicate hydrate mineral of general chemical formula: Ca9Si6O18(OH)6·8H2O.
Tobermorite is a calcium silicate hydrate mineral with chemical formula: Ca5Si6O16(OH)2·4H2O or Ca5Si6(O,OH)18·5H2O.
Fluorellestadite is a rare nesosilicate of calcium, with sulfate and fluorine, with the chemical formula Ca10(SiO4)3(SO4)3F2. It is a member of the apatite group, and forms a series with hydroxylellestadite.
Tarbuttite is a rare phosphate mineral with formula Zn2(PO4)(OH). It was discovered in 1907 in what is now Zambia and named for Percy Coventry Tarbutt.
Collinsite is a mineral with chemical formula Ca
2(Mg,Fe2+
)(PO
4)
2•2H
2O. It was discovered in British Columbia, Canada, and formally described in 1927. It was named in honor of William Henry Collins (1878–1937), director of the Geological Survey of Canada. There are three varieties of the mineral: magnesian collinsite, zincian collinsite, and strontian collinsite. The crystal structure consists of polyhedral chains linked by weak hydrogen bonds.
Ruizite is a sorosilicate mineral with formula Ca2Mn2Si4O11(OH)4·2H2O. It was discovered at the Christmas mine in Christmas, Arizona, and described in 1977. The mineral is named for discoverer Joe Ana Ruiz.
Junitoite is a mineral with formula CaZn2Si2O7·H2O. It was discovered at the Christmas mine in Christmas, Arizona, and described in 1976. The mineral is named for mineral chemist Jun Ito (1926–1978).
Bicchulite has an ideal chemical formula of 2CaO •Al2O3 •SiO2 •H2O, which was formularized from the hydrothermal synthesis of synthetic gehlenite (2CaO •Al2O3 •SiO2). Also, bicchulite was sighted in the mines of Japan with related minerals. This sodalite-type structured bicchulite has an uncommon ratio of aluminium to silicon, causing difficulties deciphering the structure. Because of bicchulite's structure it has a powdery texture, which leads to complications in obtaining information on the mineral's physical properties. Despite this problem, the color, specific gravity, and crystal size of bicchulite are known. Although bicchulite was only discovered about 40 years ago, technology has been rapidly advancing, allowing more accurate results to be made from experiments done today.
Hidalgoite, PbAl3(AsO4)(SO4)(OH)4, is a rare member of the beudantite group and is usually classified as part of the alunite family. It was named after the place where it was first discovered, the Zimapán mining district, Hidalgo, Mexico. At Hidalgo where it was initially discovered, it was found as dense white masses in alternating dikes of quartz latite and quartz monzonite alongside other secondary minerals such as sphalerite, arsenopyrite, cerussite and trace amounts of angelsite and alamosite, it was then rediscovered at other locations such as Australia where it occurs on oxidized shear zones above greywacke shales especially on the anticline prospects of the area, and on fine grained quartz-spessartine rocks in Broken Hill, Australia. Hidalgoite specimens are usually associated with copper minerals, clay minerals, iron oxides and polymetallic sulfides in occurrence.
Leifite is a rare tectosilicate. Tectosilicates are built on a framework of tetrahedra with silicon or aluminium at the centre and oxygen at the vertices; they include feldspars and zeolites, but leifite does not belong in either of these categories. It is a member of the leifite group, which includes telyushenkoite (Cs,Na,K)Na6(Be2Al3Si15O39) and eirikite KNa6Be2(Si15Al3)O39F2). Leifite was discovered in 1915, and named after Leif Ericson who was a Norse explorer who lived around 1000 AD, and was probably the first European to land in North America, nearly 500 years before Christopher Columbus. Eirikite was named in 2007 after Eirik Raude, or Erik the Red, (950–1003), who discovered Greenland and who was the father of Leif Ericson. The third mineral in the group, telyushenkoite, was discovered in 2001. It was not named after any of Leif Ericson's family members, but after a professor of geology in Turkmenistan.
Khinite is a rare tellurate mineral with the formula Pb2+Cu2+3TeO6(OH)2 It crystallizes in the orthorhombic system and has a bottle-green colour. It is often found as dipyramidal, curved or corroded crystals no more than 0.15 mm in size. The tetragonal dimorph of khinite is called parakhinite.
Effenbergerite is the natural occurrence of the color Han blue.It was first found in the Wessels mine, Kalahari Manganese Field, South Africa. Effenbergerite was approved as a valid mineral species by the IMA in 1993.
Bibliography
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