General Information:
Chemical Formula:
(Fe+++,Al)5(VO4,PO4)2(OH)9·3(H2O)
Composition:
(Molecular Weight = 670.16 gm)
Aluminum 5.03 % Al
Vanadium 11.40 % V
Iron 31.25 % Fe
Phosphorus 2.31 % P
Hydrogen 2.26 % H
Oxygen 47.75 % O
Empirical Formula:
5(Fe3+0.75)5(Al0.25)(VO4)1.5(PO4)0.5(OH)9·3(H2O)
Environment:
Found in the oxidized layers of carbonacwous shales with apatite, and Pb, Zn, and Cu sulfides.
IMA Status:
Approved IMA 1960
Locality:
Balasauskandyk, Kara Tau, Kazakhstan.
Name Origin:
Named for Mikhail Petrovich Rusakov (1892-1963), geologist, Kazakhstan, Russia.
Physical Properties:
Color:
yellow orange or reddish yellow.
Density:
2.73 - 2.8, Average = 2.76
Habits:
Reniform - "Kidney like" in shape (e.g.. hematite)., Encrustations - Forms crust-like aggregates on matrix.,
Hardness:
1.5 - Between Talc and Gypsum
Streak:
ochraceous
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