Zinnwaldite | |
---|---|
General | |
Category | Phyllosilicate mineral |
Formula (repeating unit) | KLiFeAl(AlSi3)O10(OH,F)2 |
IMA symbol | Znw [1] |
Crystal system | Monoclinic |
Crystal class | Prismatic (2/m) (same H-M symbol) |
Space group | Cc (no. 9) |
Unit cell | a = 5.29, b = 9.14 c = 10.09 [Å]; β = 100.83° |
Identification | |
Color | Gray-brown, yellow-brown, pale violet, dark green, color zoning common |
Crystal habit | Well-formed short prismatic or tabular crystals, pseudohexagonal, in rosettes or fan-shaped groups; lamellar or scaly aggregates; disseminated. |
Twinning | On composition plane {001}, twin axis [310] |
Cleavage | Perfect basal {001} |
Fracture | Uneven |
Tenacity | Laminae °exible, elastic |
Mohs scale hardness | 3.5 - 4.0 |
Luster | Pearly to vitreous |
Streak | White |
Diaphaneity | Transparent to translucent |
Specific gravity | 2.9 - 3.1 |
Optical properties | Biaxial (-) |
Refractive index | nα = 1.565 - 1.625 nβ = 1.605 - 1.675 nγ = 1.605 - 1.675 |
Birefringence | 0.040 - 0.050 |
Pleochroism | Distinct, X = colorless to yellow-brown; Y = gray-brown; Z = colorless to gray-brown |
2V angle | 0 - 40° |
References | [2] [3] [4] [5] |
Zinnwaldite, K Li Fe Al(AlSi 3)O 10(OH,F)2, potassium lithium iron aluminium silicate hydroxide fluoride is a silicate mineral in the mica group. The IMA status is as a series between siderophyllite (KFe2Al(Al2Si2)O10(F,OH)2) and polylithionite (KLi2AlSi4O10(F,OH)2) and not considered a valid mineral species. [4]
It was first described in 1845 in Zinnwald/Cinovec on the German-Czech Republic border. [4]
It occurs in greisens, pegmatite, and quartz veins often associated with tin ore deposits. It is commonly associated with topaz, cassiterite, wolframite, lepidolite, spodumene, beryl, tourmaline, and fluorite. [2]
Lepidolite is a lilac-gray or rose-colored member of the mica group of minerals with chemical formula K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2. It is the most abundant lithium-bearing mineral and is a secondary source of this metal. It is the major source of the alkali metal rubidium.
Cavansite, whose name is derived from its chemical composition, calcium vanadium silicate, is a deep blue hydrous calcium vanadium phyllosilicate mineral, occurring as a secondary mineral in basaltic and andesitic rocks along with a variety of zeolite minerals. Discovered in 1967 in Malheur County, Oregon, cavansite is a relatively rare mineral. It is polymorphic with the even rarer mineral, pentagonite. It is most frequently found in Pune, India and in the Deccan Traps, a large igneous province.
Paragonite is a mineral, related to muscovite. Its empirical formula is NaAl2(AlSi3O10)(OH)2. A wide solvus separates muscovite from paragonite, such that there is little solid solution along the vector Na+K+ and apparent micas of intermediate composition is most commonly a microscopic (or even sub-microscopic) intergrowth of two distinct micas, one rich in K, and the other in Na. Paragonite is a common mineral in rocks metamorphosed under blueschist facies conditions along with other sodic minerals such as albite, jadeite and glaucophane. During the transition from blueschist to greenschist facies, paragonite and glaucophane are transformed into chlorite and albite. Jadeite bearing pyroxene minerals have suggested Clinozoisite and paragonite are associated and derived from lawsonite releasing Quartz and water via the following reaction:
Cancrinite is a complex carbonate and silicate of sodium, calcium and aluminium with the formula Na6Ca2[(CO3)2|Al6Si6O24]·2H2O. It is classed as a member of the feldspathoid group of minerals; the alkali feldspars that are poor in silica. Yellow, orange, pink, white or even blue, it has a vitreous or pearly luster; a hardness of 5–6 and an uneven conchoidal fracture. It is unusual among the silicate minerals in that it will effervesce with hydrochloric acid due to the associated carbonate ions.
Chondrodite is a nesosilicate mineral with formula (Mg,Fe)
5(SiO
4)
2(F,OH,O)
2. Although it is a fairly rare mineral, it is the most frequently encountered member of the humite group of minerals. It is formed in hydrothermal deposits from locally metamorphosed dolomite. It is also found associated with skarn and serpentinite. It was discovered in 1817 at Pargas in Finland, and named from the Greek for "granule", which is a common habit for this mineral.
Clinozoisite is a complex calcium aluminium sorosilicate mineral with formula: Ca2Al3(Si2O7)(SiO4)O(OH). It forms a continuous solid solution series with epidote by substitution of iron(III) in the aluminium (m3 site) and is also called aluminium epidote.
Chloritoid is a silicate mineral of metamorphic origin. It is an iron magnesium manganese alumino-silicate hydroxide with formula (Fe, Mg, Mn)
2Al
4Si
2O
10(OH)
4. It occurs as greenish grey to black platy micaceous crystals and foliated masses. Its Mohs hardness is 6.5, unusually high for a platy mineral, and it has a specific gravity of 3.52 to 3.57. It typically occurs in phyllites, schists and marbles.
Siderophyllite is a rare member of the mica group of silicate minerals with formula KFe2+2Al(Al2Si2)O10(F,OH)2.
Yuksporite is a rare inosilicate mineral with double width, unbranched chains, and the complicated chemical formula K4(Ca,Na)14Sr2Mn(Ti,Nb)4(O,OH)4(Si6O17)2(Si2O7)3(H2O,OH)3. It contains the relatively rare elements strontium, titanium and niobium, as well as the commoner metallic elements potassium, calcium, sodium and manganese. As with all silicates, it contains groups of linked silicon and oxygen atoms, as well as some associated water molecules.
Ussingite is a silicate mineral with formula Na2AlSi3O8(OH).
Vanadiocarpholite (Mn+2V+3AlSi2O6(OH)4) is straw yellow to brown silicate mineral. It crystallizes in the orthorhombic crystal system. It is the vanadium rich variety of carpholite (Mn+2Al2Si2O6(OH)4).
Plancheite is a hydrated copper silicate mineral with the formula Cu8Si8O22(OH)4•(H2O). It is closely related to shattuckite in structure and appearance, and the two minerals are often confused.
Amesite is a mineral with general formula of Mg2Al2SiO5(OH)4.
Imogolite is an aluminium silicate clay mineral with the chemical formula Al2SiO3(OH)4. It occurs in soils formed from volcanic ash and was first described in 1962 for an occurrence in Uemura, Kumamoto prefecture, Kyushu Region, Japan. Its name originates from the Japanese word imogo, which refers to the brownish yellow soil derived from volcanic ash. It occurs together with allophane, quartz, cristobalite, gibbsite, vermiculite and limonite.
Narsarsukite is a rare silicate mineral with either the chemical formula Na2(Ti,Fe3+)Si4(O,F)11 or Na4(Ti,Fe)4[Si8O20](O,OH,F)4.
Minnesotaite is an iron silicate mineral with formula: (Fe2+,Mg)3Si4O10(OH)2. It crystallizes in the triclinic crystal system and occurs as fine needles and platelets with other silicates. It is isostructural with the pyrophyllite-talc mineral group.
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.
Carpholite is a manganese silicate mineral with formula Mn2+Al2Si2O6(OH)4. It occurs as yellow clusters of slender prisms or needles. It crystallizes in the orthorhombic system.
Manganiceladonite is a rare silicate mineral with the formula KMgMn3+Si4O10(OH)2. It is one of many minerals discovered in the Cerchiara mine, La Spezia, Liguria, Italy.
Alpeite (IMA symbol: Apt) is a calcium manganese magnesium silicate mineral with the chemical formula Ca4Mn3+2Al2(Mn3+Mg)(SiO4)2(Si3O10)(V5+O4)(OH)6. It is named for its type locality, the Monte Alpe mine in Italy.