Moonstone
Series / solid solution
Moonstone is feldspar (an orthoclase-albite intergrowth) showing a billowy blue-white adularescence. Compositions vary between the end-member species Orthoclase and Albite.
Photos
About Orthoclase (major)
Full reference data — crystallography, X-ray diffraction, and cited physical properties — is on the Orthoclase species page.
| Formula | K(AlSi3O8) |
|---|---|
| Hardness (Mohs) | 6-6.5 |
| Specific gravity | 2.5-2.62 |
| Density (calculated) | 2.555 |
| Crystal system | monoclinic |
| Color range | colorless, gray, green, red, white, yellow |
| Luster | vitreous |
| Streak | red |
About Albite (major)
Full reference data — crystallography, X-ray diffraction, and cited physical properties — is on the Albite species page.
| Formula | Na(AlSi3O8) |
|---|---|
| Hardness (Mohs) | 5.5 |
| Specific gravity | 2.63-2.66 |
| Density (calculated) | 2.621 |
| Crystal system | triclinic |
| Color range | red, white, yellow |
| Streak | white |