Delvauxite

Delvauxite, also known as borickite, is a yellow to brown to dark brown amorphous mineral, sometimes forming a botryoidal mass. Its chemical formula is CaFe4(PO4,SO4)2OH ⋅ xH2O. It may sometimes form stalactites.Found in Bernau, Liege, Belgium and Stredocesky, Czech republic.
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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‚, LiŠge, 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
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