Perthite

An intergrowth of Albite or Oligoclase Feldspar with a Microcline or occassionally Orthoclase host.

Perthit perthite feldspat feldspar canada Kanada
Origin of name: named after the town of Perth in Ontario, Canada

Synonyms and trade names: Anperthite

Can be confused with: other Feldspars, brownish Thulite

Localities: Perthite is found on all continents, even in Antarctica, but only rarely used as a gem stone or ornamental stone

Handling: Due to the perfect cleavage Perthite has to be set with extreme care. Sensitive to acid and brine.

Gemmological Properties of Perthite

Mohs hardness:
6-6.5
Specific gravity:
2.5-2.8
Refractive index:
1,518 to 1,588
Max. Birefringence:
0,005 to 0,013
Luminiscence:
patchy, bluish or greenish
Lustre:
vitreous
Cleavage:
perfect
Fracture:
conchoidal
Colour:
brownish white to reddish brown