General Information:
Chemical Formula:
[ ](Li2Mg3Al2)Si8O22(OH)2
Composition:
(Molecular Weight = 751.45 gm)
Lithium 1.85 % Li
Magnesium 9.70 % Mg
Aluminum 7.18 % Al
Silicon 29.90 % Si
Hydrogen 0.27 % H
Oxygen 51.10 % O
Empirical Formula:
Li2Mg3Al2(Si8O22)(OH)2
Environment:
Wall rock and contact zones of lithian pegmatites with basic or ultrabasic country rock.
IMA Status:
Approved IMA 1978
Locality:
Uto Island, Sondermanland, Sweden.
Name Origin:
Named for Per Johan Holmquist (1866-1946), petrologist, Stockhom, Sweden.
Physical Properties:
Cleavage:
[210] Perfect
Color:
blue, violet, light blue, dark violet, or black.
Density:
3.06 - 3.13, Average = 3.09
Diaphaniety:
Transparent to Translucent
Habits:
Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline)., ,
Hardness:
5.5 - Knife Blade
Luster:
Vitreous (Glassy)
Streak:
bluish white
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