Sturmanite

Formula: Ca6(Fe,Al,Mn)2(SO4)2[B(OH)4](OH)12.25H2O

Origin of name: for B. Darko Sturman, Croatian-Canadian mineralogist

 

Crystal system: hexagonal

Crystal class: 3m

Twinning: 

Unit cell: a = 11.16 Å, c = 21.79 Å

 

Colour: bright yellow to yellow-green

Diaphaneity: 

Luster: vitreous

Habit: crystals stubby to elongated prismatic, dipyramidal, to 2 cm

Hardness: 2.5

Specific gravity: 1.847

Cleavage: 1; {10-10} perfect

Tenacity: 

Streak: 

 

Synonyms/varieties:

 

Comments: 

 

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