General Information:
Chemical Formula:
CaFe+++4(PO4,SO4)2(OH)8·4-6(H2O) (?)
Composition:
(Molecular Weight = 320.74 gm)
Iron 34.82 % Fe
Phosphorus 9.66 % P
Hydrogen 3.14 % H
Oxygen 52.38 % O
Empirical Formula:
Fe3+2(PO4)(OH)3·3.5(H2O)
Locality:
Berneau, near Vis, Lige, Belgium.
Name Origin:
Named after J.S.P.J. Delvaux de Feuffe (1782-1863), Belgian chemist who first described and analyzed the mineral.
Physical Properties:
Cleavage:
None
Color:
yellowish brown, brown, reddish brown, or brownish black.
Density:
1.8 - 2, Average = 1.9
Habits:
Amorphous - No crystalline form or imitative shape., Concretionary - Rounded massive fine-grained materials., Stalactitic - Shaped like pendant columns as stalactites or stalagmites ( e.g. calcite).
Hardness:
2.5 - Finger Nail
Luster:
Vitreous - Greasy
Streak:
yellow
More details...