General Information:
Chemical Formula:
CaAl2Si2O8
Composition:
(Molecular Weight = 277.41 gm)
Sodium 0.41 % Na
Calcium 13.72 % Ca
Aluminum 18.97 % Al
Silicon 20.75 % Si
Oxygen 46.14 % O
Empirical Formula:
Na0.05Ca0.95Al1.95Si2.05O8
Environment:
Magmatic and metamorphic rocks.
Locality:
Monte Somma and Valle di Fassa, Italy.
Name Origin:
From the Greek, an + orthos, "not upright" in allusion to the oblique crystals.
Physical Properties:
Cleavage:
[001] Perfect, [010] Good
Color:
colorless, gray, white, red, or reddish gray.
Density:
2.72 - 2.75, Average = 2.73
Diaphaniety:
Transparent to Subtransparent to translucent
Habits:
Granular - Generally occurs as anhedral to subhedral crystals in matrix., Euhedral Crystals - Occurs as well-formed crystals showing good external form., Striated - Parallel lines on crystal surface or cleavage face.
Hardness:
6 - Orthoclase
Luminescence:
None.
Luster:
Vitreous (Glassy)
Streak:
white
More details...