Phosphosiderite

Formula: FePO₄.2H₂O

Origin of name: from phosphate and sideros = iron

Crystal system: monoclinic

Crystal class: 2/m

Twinning: common on {101} penetration

Unit cell: a = 5.33 Å, b = 9.60 Å, c = 8.71 Å, b = 90.5°

Colour: reddish violet, red, purple, wine yellow, nearly colourless

Diaphaneity: 

Luster: vitreous to subresinous

Habit: crystals tabular or stout prismatic, botryoidal crusts, massive, radial-fibrous

Hardness: 3.5 to 4

Specific gravity: 2.76

Cleavage: 2; {010} good, {001} indistinct

Tenacity: uneven, brittle

Streak: 

Synonyms/varieties: clinostrengite, metastrengite

Comments: dimorphous with strengite