Perthite or perthitic texture is used to describe an intergrowth of two feldspars: a host grain of potassium -rich alkali feldspar (near K-feldspar, KAlSi 3 O 8, in composition) includes exsolved lamellae or irregular intergrowths of sodic alkali feldspar (near albite, NaAlSi 3 …

Named for the nearby city of Perth in Ontario. The type locality is 6 miles (approx 9.5 km) southwest of Perth. A variety of Feldspar Group An intergrowth of albite or oligoclase with a microcline host, occasionally also with an orthoclase host.

A perthite is an intimate intergrowth of sodic and potassic feldspar resulting from subsolidus exsolution (unmixing of two minerals). Strictly speaking a perthite has blebs or irregular lamellae of sodic feldspar within potassic alkali feldspar, however, the term perthite is often used to describe all types of exsolution in the feldspars.

perthite, any member of a class of alkali feldspars in which tiny crystals of sodium-rich feldspar (albite; NaAlSi 3 O 8) are intimately intergrown with, but distinct from, tiny crystals of potassium-rich feldspar (orthoclase or, less commonly, microcline; KAlSi 3 O 8).

To distinguish the difference between perthite and antiperthite is to determine which the predominant feldspar is. If K-feldspar predominates, it is a perthite. If Albite predominates, it is an antiperthite.

The meaning of PERTHITE is a feldspar rock consisting of orthoclase or microcline in which is interlaminated albite.

Perthite is a blend of microcline, albite and oligoclase. It is usually brown and white. May have gold or white iridescence.

Apr 21, 2024 · Perthite describes an intimate intergrowth of alkali feldspars, in which sodium plagioclase lamellae, blebs, or droplets exsolve in potassium feldspar. To exsolve means to umix or segregate an initially homogenous solution into various components.

Perthite is an intergrowth of two different Feldspar minerals in one rock. Perthite is usually composed of vein s or stripes of one feldspar running through a different feldspar. There are many different types of Perthite. Perthite combinations are of Albite (and sometimes Oligoclase) intermixed with either Microcline or Orthoclase.

Mircoperthite is only seen microscopically, cryptoperthite is submicroscopic and needs x-ray diffraction to see extremely fine lamellae. Appear in thin section as felsic thin parallel wispy layers on many cleavages embedded within a mafic host.