Cassiterite

Cassiterite
4447M-cassiterite.jpg
Cassiterite with muscovite, from Xuebaoding, Huya, Pingwu, Mianyang, Sichuan, China (size: 100 x 95 mm, 1128 g)
General
CategoryOxide minerals
Formula
(repeating unit)
SnO2
Strunz classification4.DB.05
Crystal systemTetragonal
Crystal classDitetragonal dipyramidal (4/mmm)
H-M symbol: (4/m 2/m 2/m)
Space groupP42/mnm
Unit cella = 4.7382(4) Å,
c = 3.1871(1) Å; Z = 2
Identification
ColorBlack, brownish black, reddish brown, red, yellow, gray, white; rarely colorless
Crystal habitPyramidic, prismatic, radially fibrous botryoidal crusts and concretionary masses; coarse to fine granular, massive
TwinningVery common on {011}, as contact and penetration twins, geniculated; lamellar
Cleavage{100} imperfect, {110} indistinct; partings on {111} or {011}
FractureSubconchoidal to uneven
TenacityBrittle
Mohs scale hardness6–7
LusterAdamantine to adamantine metallic, splendent; may be greasy on fractures
StreakWhite to brownish
DiaphaneityTransparent when light colored, dark material nearly opaque; commonly zoned
Specific gravity6.98–7.1
Optical propertiesUniaxial (+)
Refractive indexnω = 1.990–2.010 nε = 2.093–2.100
Birefringenceδ = 0.103
PleochroismPleochroic haloes have been observed. Dichroic in yellow, green, red, brown, usually weak, or absent, but strong at times
Fusibilityinfusible
Solubilityinsoluble
References[1][2][3][4][5]

Cassiterite is a tin oxide mineral, SnO2. It is generally opaque, but it is translucent in thin crystals. Its luster and multiple crystal faces produce a desirable gem. Cassiterite has been the chief tin ore throughout ancient history and remains the most important source of tin today.[2]

Occurrence

Cassiterite bipyramids, edge length ca. 30 mm, Sichuan, China

Most sources of cassiterite today are found in alluvial or placer deposits containing the resistant weathered grains. The best sources of primary cassiterite are found in the tin mines of Bolivia, where it is found in hydrothermal veins. Rwanda has a nascent cassiterite mining industry. Fighting over cassiterite deposits (particularly in Walikale) is a major cause of the conflict waged in eastern parts of the Democratic Republic of the Congo.[6][7] This has led to cassiterite being considered a conflict mineral.

Cassiterite is a widespread minor constituent of igneous rocks. The Bolivian veins and the old exhausted workings of Cornwall, England, are concentrated in high temperature quartz veins and pegmatites associated with granitic intrusives. The veins commonly contain tourmaline, topaz, fluorite, apatite, wolframite, molybdenite, and arsenopyrite. The mineral occurs extensively in Cornwall as surface deposits on Bodmin Moor, for example, where there are extensive traces of an hydraulic mining method known as streaming. The current major tin production comes from placer or alluvial deposits in Malaysia, Thailand, Indonesia, the Maakhir region of Somalia, and Russia. Hydraulic mining methods are used to concentrate mined ore, a process which relies on the high specific gravity of the SnO2 ore, of about 7.0.

Other Languages
Afrikaans: Kassiteriet
العربية: كاسيتريت
asturianu: Casiterita
azərbaycanca: Kassiterit
беларуская: Касітэрыт
català: Cassiterita
čeština: Kasiterit
Deutsch: Kassiterit
Ελληνικά: Κασσιτερίτης
español: Casiterita
Esperanto: Kasiterito
euskara: Kasiterita
فارسی: کاسیتریت
français: Cassitérite
Gaeilge: Caisiteirít
galego: Casiterita
한국어: 석석
հայերեն: Կասիտերիտ
italiano: Cassiterite
עברית: קסיטריט
қазақша: Касситерит
Кыргызча: Касситерит
lietuvių: Kasiteritas
magyar: Kassziterit
Bahasa Melayu: Kasiterit
Nederlands: Cassiteriet
日本語: 錫石
norsk nynorsk: Kassiteritt
occitan: Cassiterita
oʻzbekcha/ўзбекча: Kassiterit
polski: Kasyteryt
português: Cassiterita
română: Casiterit
русский: Касситерит
Simple English: Cassiterite
slovenčina: Kasiterit
slovenščina: Kasiterit
svenska: Kassiterit
українська: Каситерит
Tiếng Việt: Cassiterit
中文: 锡石