Microcline
| Colour | White, Green, Pink |
|---|---|
| Mohs hardness | 6–6.5 |
| Lustre | Vitreous |
| Streak | White |
| Crystal system | Triclinic |
| Transparency | Transparent, translucent |
| Cleavage | Has perfect cleavage parallel to {001} and good cleavage on {010}. Cleavages intersect at 90°41'. It can be difficult to see cleavage in thin section due to microcline's low relief |
| Fracture | Uneven |
| Chemical formula | KAlSi 3 O 8 |
| Specific gravity | 2.5–2.6 |
What is Microcline?
Microcline (KAlSi3O8) is an important igneous rock-forming tectosilicate mineral. It is a potassium-rich alkali feldspar. It is common in granite and pegmatites. Microcline forms during slow cooling of orthoclase. Sanidine is a polymorph of alkali feldspar stable at yet higher temperature. Microcline has cross-hatch twinning that forms as a result of the transformation of monoclinic orthoclase into triclinic microcline.
How to identify Microcline
- Lustre: Vitreous.
- Hardness: Mohs 6–6.5 — about as hard as a steel knife.
- Streak: White.
- Habit: Triclinic crystal system.
Microcline in different forms
Stones often confused with Microcline
Frequently asked questions
How hard is Microcline?
Microcline is Mohs 6–6.5 on the hardness scale.
What colour is Microcline?
Microcline is typically white, green, pink (White, grey, greyish yellow, yellowish, tan, salmon-pink, bluish green, green).