Microcline vs Plagioclase
Microcline and Plagioclase belong to the same mineral group and differ on 1 measured property — density most clearly.
Microcline vs Plagioclase
Microcline
KAlSi3O8
Potassium feldspar's low-temperature form — chemically identical to orthoclase, structurally ordered, and the source of the green gemstone amazonite.
Plagioclase
(Na,Ca)Al(Si,Al)Si2O8
A continuous solid solution from sodium to calcium feldspar — the commonest mineral series in the crust, and a thermometer for the magma that grew it.
| Property | Microcline | Plagioclase |
|---|---|---|
| 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 about 86 degrees |
| Crystal system Categorical values can be listed side by side but not ordered or subtracted. | triclinic | triclinic |
| Density | 2.54–2.57 g/cm³ | 2.62–2.76 g/cm³ higher |
| Lustre Only one of the two has a figure we can stand behind, so there is nothing to compare. | vitreous | Not known |
| Mohs hardness Mohs hardness is an ordinal scale: values can be ranked, but differences and ratios between them are not meaningful. | 6–6.5 | 6–6.5 |
| Streak Only one of the two has a figure we can stand behind, so there is nothing to compare. | white | Not known |