Tenacity
-
Very brittle
Solubility
-
insoluble
Durability
-
-
Specific Gravity
2.74-2.763.30-3.40
1
7.18
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Fracture
Uneven
Conchoidal
Cleavage
{010} Perfect, {001} Distinct
{010} perfect, {110} distinct, {100} in traces
Mohs Hardness
3.5-46.5-7
2
10
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Chemical Composition
Fe3+ PO 4 · 2H 2OAnthony et al , Handbook of Mineralogy (2001)
AlO(OH)Walter Schumann , Gemstones of the world (2001) More from other references