zinnwaldite

This article is about the mineral. For the color, see Zinnwaldite (color). Zinnwaldite, KLiFeAl(AlSi3)O10(OH,F)2, is a potassium lithium iron aluminium silicate hydroxide fluoride silicate mineral in the mica group.It occurs in greisens, pegmatite and quartz veins often associated with tin ore deposits. Commonly associated with topaz, cassiterite, wolframite, lepidolite, spodumene, beryl, tourmaline and fluorite.It was first described in 1845 in Zinnwald (http://de.wikipedia.org/wiki/Zinnwald), Germany.
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Noun
1. a mica containing iron and lithium
(hypernym) mica, isinglass
(substance-meronym) lithium, Li, atomic number 3

(n.)
A kind of mica containing lithium, often associated with tin ore.
  

General Information:
 Chemical Formula:
KLiFe++Al(AlSi3)O10(F,OH)2
 Composition:
(Molecular Weight = 437.10 gm)
Potassium 8.94 % K 
Lithium 1.59 % Li
Aluminum 12.35 % Al
Iron 12.78 % Fe
Silicon 19.28 % Si
Hydrogen 0.12 % H 
Oxygen 38.43 % O 
Fluorine 6.52 % F 
 Empirical Formula:
KLiFe2+Al2Si3O10F1.5(OH)0.5
 Environment:
Pneumatolytic mineral occurring in cassiterite and topaz-bearing pegmatites.
 Locality:
Erzgebirge of Saxony at Zinnwald (now Cinovec) - "Ore Mountains", Czechoslovakia.
 Name Origin:
Named after its locality.
Physical Properties:
 Cleavage:
[001] Good
 Color:
light brown, silvery white, gray, yellowish white, or greenish white.
 Density:
2.9 - 3.1, Average = 3
 Diaphaniety:
Transparent
 Habits:
Pseudo Hexagonal - Crystals show a hexagonal outline., Micaceous - Platy texture with "flexible" plates., Platy - Sheet forms (e.g. micas).
 Hardness:
3.5-4 - Copper Penny-Flourite
 Luminescence:
None.
 Luster:
Vitreous - Pearly
 Streak:
white
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ZINNWALDITE