Mineralogy and Crystallography

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micas

A Dictionary of Earth Sciences | 1999 | | Copyright

micas An important group of phyllosilicates (sheet silicates) with a 2:1 atomic structure (see CLAY MINERALS) and including the important minerals muscovite, biotite, and phlogopite; the group is characterized by the silicon oxygen tetrahedral layers of composition [Si₄O₁₀]_n and a general composition may be written (K,Na)₂Y₆[Z₄O₁₀]₂(OH,F)₄, where Y = Mg, Fe, Fe³⁺, or Al, and Z = Si or Al; the micas include the common micas already mentioned, plus glauconite, lepidolite, and zinnwaldite, the brittle micas (see MARGARITE), and also the related minerals talc, stilpnomelane, and pyrophyllite.

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AILSA ALLABY and MICHAEL ALLABY. "micas." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>.

AILSA ALLABY and MICHAEL ALLABY. "micas." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O13-micas.html

AILSA ALLABY and MICHAEL ALLABY. "micas." A Dictionary of Earth Sciences. 1999. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-micas.html

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lepidolite

A Dictionary of Earth Sciences | 1999 | | Copyright

lepidolite Lithium-bearing mica with composition K₂(Li,Al)_5–6 [Si_6–7A1_2–1 O₂₀] (OH,F)₄; Sp. gr. 2.8–2.9; hardness 2.5–4.0; monoclinic; crystals as small flakes; perfect basal hardness cleavage; lilac to greyish; occurs in late-stage pegmatites associated with other lithium minerals, such as spodumene, and minerals of a pneumatolytic origin, such as tourmaline and topaz. Lepidolite is an important ore mineral of lithium.

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AILSA ALLABY and MICHAEL ALLABY. "lepidolite." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>.

AILSA ALLABY and MICHAEL ALLABY. "lepidolite." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O13-lepidolite.html

AILSA ALLABY and MICHAEL ALLABY. "lepidolite." A Dictionary of Earth Sciences. 1999. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-lepidolite.html

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Free newspaper and magazine articles

	Mica from northern New Mexico pegmatites. (New Mexico Afield). Magazine article from: Corrections Today; 12/1/2000
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