Amblygonite

Formula:  (Li,Na)Al(PO4)(F,OH)

Origin of name:  From Greek amblys and goni for blunt and angle

 

Crystal system: Triclinic

Crystal class:  -1

Twinning:  Common on {-1-11}; on {110}; rare on {111}

Unit cell:   a = 5.15 Å, b = 7.22 Å, c = 5.06 Å, a = 114.0°, b = 98.6°, g = 67.3°

 

Colour:  White to grayish white, also colourless, pink, tan, greenish, bluish

Diaphaneity: Transparent to translucent

Luster:  Vitreous to greasy, pearly on cleavage

Habit:  Crystals equant to short prismatic; usually large cleavable masses

Hardness:  5.5 to 6

Specific gravity:  3.08

Cleavage:  4; {100} perfect, {110} good, {0-11} distinct, {001} imperfect

Tenacity:  Brittle

Streak: White

 

Synonyms/varieties:

 

Comments:  Series with montebrasite

 

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