Aheylite

Formula:  (Fe, Zn)Al₆(PO₄)₄(OH)₈.4H₂O

Origin of name:  for Allen V. Heyl (1918- ), American economic geologist, US Geological Survey

Crystal system:  Triclinic

Crystal class:  1 or -1

Twinning:

Unit cell: a = 7.400 Å, b = 9.896 Å, c = 7.627 Å, a = 110.87°, b = 115.00°, g = 69.96°

Colour:  Very pale blue, pale green to blue-green

Diaphaneity: Translucent

Luster: Porcelaneous to subvitreous

Habit: As crystals, interlocked in felted or matted aggregates to form botryoidal, spherulitic masses; radiating prismatic groups to 5 mm

Hardness:  5-5.5

Specific gravity:  2.85

Cleavage:  None

Tenacity: May be brittle

Streak: White

Synonyms/varieties:

Comments: Member of the turquoise group. Formed as a late state hydrothermal mineral in a base-metal-tin deposit.