A ghostly sheen moves under the surface of this feldspar, like moonlight glowing in water.


Moonstone is the opalescent variety of orthoclase, with a blue or white sheen (or “schiller”), rather like the shine of the moon after which it is named. This is caused by the reflection of light from the internal structure, made up of alternating layers of albite and ortho- clase feldspar. Thin albite layers give an attractive blue; thicker layers produce a white “schiller”. Stones of large size and fine quality are rare.


The best material is from Burma and Sri Lanka. Other localities include India, Madagascar, Brazil, the USA, Mexico, Tanzania, and the European Alps.

Fun Facts

Moonstone’s unearthly glow is caused by light scattering between microscopic layers of feldspar.
The minerals in the feldspar family make up more than half of the Earth’s rocky crust.
Feldspar layers that create moonstone’s sheen are similar to the size of a wavelength of light.
Birthstone June
Crystal Structure Monoclinic
Composition Potassium Aluminium
Luster Vitreous
Hardness 6
Refractive Index 1.52 to 1.53
Specific Gravity 2.57
Mohs Hardness 3
DR 0.005