Microcline vs Orthoclase
Microcline and Orthoclase are commonly confused, and 3 measured properties separate them — crystal system most clearly.
Microcline vs Orthoclase
Microcline
KAlSi3O8
Potassium feldspar's low-temperature form — chemically identical to orthoclase, structurally ordered, and the source of the green gemstone amazonite.
Orthoclase
KAlSi3O8
The potassium feldspar of granite — the most abundant mineral group in the Earth's crust, and the raw material of porcelain.
| Property | Microcline | Orthoclase |
|---|---|---|
| Cleavage Only one of the two has a figure we can stand behind, so there is nothing to compare. | Not known | perfect in one direction, good in a second at right angles |
| Crystal system Categorical values can be listed side by side but not ordered or subtracted. | triclinic | monoclinic |
| Density | 2.54–2.57 g/cm³ | 2.55–2.63 g/cm³ higher |
| Lustre Categorical values can be listed side by side but not ordered or subtracted. | vitreous | vitreous |
| Mohs hardness Mohs hardness is an ordinal scale: values can be ranked, but differences and ratios between them are not meaningful. | 6–6.5 higher | 6 |
| Streak Categorical values can be listed side by side but not ordered or subtracted. | white | white |
Why these get confused
identical composition and indistinguishable in hand specimen; separated by cross-hatched twinning under crossed polarisers
The confusion is a real and documented one, not a resemblance we have invented.