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Sheet silicate subclass

Sheet silicate subclass

Margarite

Hand Specimen identification: Margarite is characterized by its micaceous nature, brittleness, and pearly luster. Association and brittle-ness usually distinguish it from other white micas. Chemical Composition : CaAl2(Al2Si 2O10)(OH)2 Hardness : 31 2 to 5 Specific Gravity3.1 Cleavage/Fracture : perfect basal (001)/uneven Luster/Transparency : vitreous/transparentto translucentvitreous/transparentto translucent Color : gray-yellow, …

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Lepidolite

Hand Specimen identification: Micaceous habit (see Figure 11), often a distinctive lilac-gray or rose color, and association usually serve to identify lepidolite. Chemical Composition : K(Li,Al) 2 – 3(AlSi 3O10)(OH)2 Hardness : 2.5 to 4 Specific Gravity2.9 Cleavage/Fracture : perfect basal {001}/uneven Luster/Transparency : pearly/translucent Color : perfect basal {001}/uneven …

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Muscovite

Hand Specimen identification: Micaceous character (Figure 10a) and silver color distinguish muscovite. It may be confused with other white micas, such as paragonite or margarite. Certain identification requires optical, X-ray, or chemical analysis. Chemical Composition : KAl2(AlSi 3O10)(OH)2 Hardness : 2 to 2 1 2 Specific Gravity2.8 Cleavage/Fracture : perfect …

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Chlorite

Hand Specimen identification: Deep green color, and micaceous habit and cleavage are usually adequate to identify chlorite. The many individual species and varieties are difficult to tell apart. Chlorite is sometimes confused with talc. Chemical Composition : (Mg,Fe,Al)6(Si,Al)4O10(OH)8 Hardness : 2 to 21 2 Specific Gravity3 Cleavage/Fracture : perfect basal …

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Apophyllite

Hand Specimen identification: Like prehnite, apophyllite often occurs where zeo-lites occur. Perfect one direction of cleavage, form, color, and luster help identify it. Chemical Composition : KCa4Si8O20F#8H2O Hardness : 41 2 to 5 Specific Gravity2.3 Cleavage/Fracture : one perfect (001), poor{110}/uneven Luster/Transparency : pearly/transparentto translucent Color : colorless, white, gray …

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Prehnite

Hand Specimen identification: Prehnite, although not a zeolite, occurs in many of the same places that zeolites occur. When green and botryoidal (typical) it is easily identified. Otherwise it may be difficult to distinguish from zeolites, and may also be confused with hemimorphite and smithsonite. Chemical Composition : Ca2Al(AlSi 3O10)(OH)2 …

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Antigorite

Hand Specimen identification: Green color, greasy luster, lack of cleavage, and as-sociation identify antigorite. Chrysotile is a more fibrous variety of serpentine. Chemical Composition : Mg6Si4O10(OH)8 Hardness : 3 to 4 Specific Gravity2.6 Cleavage/Fracture : perfect (001)/flexible Luster/Transparency : resinous, silky/translucent Color : green, yellow-green Streak : white Optical Properties …

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Chrysotile

Hand Specimen identification: Fiberlike, asbestiform appearance is diagnostic (Figure 8). Chrysotile may be distinguished from most fibrous amphiboles by its greenish white color; com-pare Plates 3.4 and 3.7. Chemical Composition : Mg6Si4O10(OH)8 Hardness : 3 to 5 Specific Gravity2.5 to 2.6 Cleavage/Fracture : none/uneven Luster/Transparency : greasy, waxy/translucent Color : …

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Kaolinite

Hand Specimen identification: Claylike properties, including softness, habit, feel, and earthy smell, help identify kaolinite, but withoutX-ray data it cannot be distinguished from other light-colored clays. Chemical Composition : Al2Si2O5(OH)4 Hardness : 2 to 21 2 Specific Gravity2.6 Cleavage/Fracture : perfect (001) but rarely seen Luster/Transparency : dull/sometimes translucent Color …

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Talc

Hand Specimen identification: Softness, greasy feel, massive habit, cleavage, and association help identify talc. It may be confused with pyrophyllite, serpentine, or chlorite. Chemical Composition : Mg3Si4O10(OH)2 Hardness : 1 Specific Gravity2.8 Cleavage/Fracture : perfect basal (001)/flexible Luster/Transparency : resinous, silky/translucent Color : gray, white Streak : white Optical Properties …

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