General Information:
Chemical Formula:
(K2,Na2,Ca,Mg)2[Al4Si14O36]·15(H2O)
Environment:
Occurs in volcanic and sedimentary rocks. Common in altered silicic tuff., especially in saline lacustrine deposits.
Locality:
Durkee opal mine, Suayze Creek, near Durkee, Baker Co., Oregon, USA.
Name Origin:
From the Greek for wool, in allusion to its white, fibrous, wool-like appearance.
Physical Properties:
Cleavage:
[010] Distinct
Color:
white, green, gray, or orange.
Density:
2.09 - 2.13, Average = 2.11
Diaphaniety:
Transparent to translucent
Habits:
Acicular - Occurs as needle-like crystals., ,
Hardness:
3.5-4 - Copper Penny-Flourite
Luminescence:
Non-fluorescent.
Luster:
Vitreous - Silky
Streak:
white
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