General Information:
Chemical Formula:
(Ca,Fe++,Mn,Na)2(Sb,Ti)2O6(O,OH,F)
Name Origin:
Named after the French crystallographer, J. B. Rome de I'lsle (1736-1770).
Physical Properties:
Cleavage:
[111] Imperfect, [111] Imperfect, [111] Imperfect
Color:
white, yellow, or yellowish brown.
Density:
4.7 - 5.4, Average = 5.05
Diaphaniety:
Transparent to Subopaque
Habits:
Encrustations - Forms crust-like aggregates on matrix., Pulverulent - Forms a loose, poorly-coherent powdery mass.,
Hardness:
5.5-6 - Knife Blade-Orthoclase
Luster:
Vitreous - Greasy
Streak:
brownish yellow
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