Aminoffite

Formula:  Ca₃(Be,Al)₂Si₃O₁₀(OH)₂

Origin of name:  For Gregori Aminoff (1883-1947), Swedish mineralogist and expert on Långban mineralogy, associated with the Riksmuseum Stockholm, Sweden

Crystal system:  Tetragonal

Crystal class:  4/m

Twinning: common, polysynthetic on {001}

Unit cell:  a = 9.806 Å, c = 9.919 Å

Colour:  Colourless, pale yellow

Diaphaneity: Transparent

Luster:  Vitreous

Habit:  Crystals pyramidal

Hardness:  5.5-6

Specific gravity:  2.94

Cleavage:  1; {001} imperfect

Tenacity:  Brittle

Streak: White

Synonyms/varieties:

Comments: Observed in cavities in massive magnetite; in fluorite veins at the contact between marbles and "hornblende"granites associated with hastingite nepheline syenites; in fluorite veins in tinguaite and nepheline dikes