THE MINERAL TARBUTTITE

Chemistry: Zn2(PO4)(OH), Zinc Phosphate Hydroxide.
Class: Phosphates
Uses: only as a mineral specimen.
Specimens

Tarbuttite is a somewhat rare phosphate mineral but is popular among collectors of rare minerals, especially rare phosphates. It forms good crystals and has a nice luster. Occasionally, the colors can be rather attractive although they are commonly known to be pale. It is usually associated with the colorful limonite, an iron oxide, and the combination can make for a nice cabinet specimen.

PHYSICAL CHARACTERISTICS:

Color is colorless and pale white, red, green, yellow or brown.
Luster is vitreous.
Transparency crystals are transparent to translucent.
Crystal System is triclinic, bar 1
Crystal Habits include deeply striated prismatic crystals or crusts.
Cleavage is perfect in one direction.
Hardness is 3.5 - 3.7
Specific Gravity is approximately 4.2 (heavy for translucent minerals)
Streak is white.
Associated Minerals are limonite, smithsonite and some other oxidized zinc ore deposit minerals.
Notable Occurrences include Broken Hill, Shaba, Zambia and elsewhere.
Best Field Indicators are crystal habit, locality, associations with other zinc ores and/or phosphate minerals and density.