Identification guide · Silicate Minerals
How to Identify Microcline
Microcline is usually white, cream, and pink with a vitreous luster and is translucent. It has a Mohs hardness of 6. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Its streak is white. It is most often confused with Albite, Nepheline, and Feldspar; the tests below separate them.
Microcline identification checklist
| Color | White, Cream, Pink, Green, Gray | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Vitreous | Fresh surfaces shine like glass; a dull surface usually means weathering, so chip or wet a corner. |
| Transparency | Translucent | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 6 | It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. |
| Streak | White | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Perfect on {001}, good on {010} | |
| Fracture | Uneven | |
| Specific gravity | 2.56 | Ordinary rock-like heft (specific gravity about 2.56), similar to quartz. |
| Crystal system | Triclinic |
Microcline look-alikes and how to tell them apart
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Microcline vs Albite →
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Microcline vs Nepheline →
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Microcline vs Feldspar →
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Microcline vs Leucite →
Field tips
- Look for two cleavage directions meeting at nearly right angles and a hardness of about 6.
- Blue-green color suggests the amazonite variety, but confirm with cleavage and crystal habit.
- Microcline is difficult to tell from orthoclase by eye; a microscope reveals its tartan twinning.
Microcline identification FAQ
How can you tell if a rock is Microcline?
Check the color (white, cream, pink, and green), the vitreous luster, a Mohs hardness of 6 and a white streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Microcline?
Microcline has a Mohs hardness of 6. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
What is the difference between Microcline and Albite?
Microcline (Mohs 6, vitreous luster) and Albite (Mohs 6–6.5, vitreous, pearly on cleavage luster) look alike, but hardness, streak and heft usually separate them. See the full Microcline vs Albite comparison for a side-by-side table.
Is Microcline worth anything?
Entry-level Microcline specimens sell for around $5, typical collector pieces about $40, and premium examples $300 or more depending on size, quality and locality.
What color is Microcline?
Microcline is most often white, cream, pink, and green. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
