Berryite

Formula:  Pb₃(Ag,Cu)₅Bi₇S₁₆

Origin of name:  For Prof. Leonard Gascoine Berry (1914-1982), Canadian mineralogist, Queen's University, Toronto, Canada. First obtained the X-ray diffraction powder of this mineral

Crystal system:  Monoclinic

Crystal class:  2/m

Twinning: Repeated

Unit cell: a = 12.72 Å, b = 4.02 Å, c = 58.07 Å, b = 102.5°

Colour:  Lead-gray

Diaphaneity:  Opaque

Luster:  Metallic

Habit:  Crystals lath-like, tiny

Hardness:  3 to 3.5

Specific gravity:  6.7

Cleavage:  None

Tenacity:

Streak:

Synonyms/varieties:

Comments: Found in quartz veins with other sulfides and sulfosalts, and in siderite-rich cryolite