Perthite is either microcline or orthoclase with thin lamellae of exsolved albite. It contains quartz and microcline feldspar and brown biotite and also muscovite. The feldspar is usually orthoclase, but can also be albite, oligoclase or microcline. Typically the host grain is orthoclase or microcline, and the lamellae are albite. It contains microcline, and few feldspar phenocrysts. It occurs associated with aegirine, microcline, albite, elpidite, epididymite, taeniolite, pectolite, calcite, galena and quartz. Associated minerals include arfvedsonite, aegirine, apatite and fluorite, in addition to microcline, albite and eudialyte. Potassium feldspar can show perthite textures, carlsbad twinning, and, in microcline, tartan twinning. However, microcline is commonly poikilitic, with abundant fine-grained plagioclase and quartz. The illustration shows tartan-twinned microcline having completely replaced plagioclase. At yet lower temperatures, microcline, a triclinic polymorph of potassium feldspar, is stable. This is a crystallized stone, a green variety of microcline feldspar. Its composition is mainly granodiorite with phenocrysts of microcline. Mineral examples include plagioclase, microcline, rhodonite, turquoise, wollastonite and amblygonite, all in triclinic normal (). Certain minerals are practically confined to deep-seated intrusive rocks, e.g., microcline, muscovite, diallage.