GEMMOLOGICAL PROPERTIES

Moonstone

Family:

Feldspar

Crystal System:

Monoclinic

Specific Gravity:

2.55 to 2.58

Hardness:

6.0 - 6.5

Refractive Index:

1.518 to 1.552

Chemical Composition:

(K, Na) AlSi3O8

Birefringence:

-0.007 to -0.008

Pleochroism:

None

Lustre:

Vitreous to Pearly

Fracture:

Irregular

Cleavage:

Good