General Information:
Chemical Formula:
(Na,K)AlSiO4
Composition:
(Molecular Weight = 146.08 gm)
Potassium 6.69 % K
Sodium 11.80 % Na
Aluminum 18.47 % Al
Silicon 19.23 % Si
Oxygen 43.81 % O
Empirical Formula:
Na0.75K0.25Al(SiO4)
Environment:
Silica-poor igneous rocks.
Locality:
Magnet Cove, Magnet Cove, Ouachita Mountains, Hot
Name Origin:
From the Greek nephele, "cloud," because it becomes clouded when put in strong acid.
Physical Properties:
Cleavage:
[1010] Poor
Color:
white, gray, brown, brownish gray, or reddish white.
Density:
2.55 - 2.65, Average = 2.59
Diaphaniety:
Transparent to translucent to opaque
Habits:
Massive - Granular - Common texture observed in granite and other igneous rock., Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).,
Hardness:
6 - Orthoclase
Luminescence:
None.
Luster:
Vitreous - Greasy
Streak:
white
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