What is plagioclase feldspar used for?
Plagioclase is used in the manufacture of glass and ceramics; the iridescent varieties peristerite and labradorite are valued as gemstones or ornamental material. The primary importance of plagioclase, however, derives from its role in rock formation.
Why do we commonly see zoned plagioclase?
Zoning results from the mineral’s inability to maintain chemical equilibrium with a magma during rapid cooling; the zonation represents a frozen picture of the continuous reaction series for that mineral. Zoning can be of three types, the first two applying mostly to plagioclase feldspars.
What is normal zoning in a plagioclase?
Normal or continuous zoning: zoning in which the outer portions of the crystal have a lower-temperature composition than the core. Usually reflects progressive change of melt composition during growth of the crystal. Plagioclases are normally zoned from calcic cores to more sodic rims.
What is meant by mineral zoning?
Quick Reference. The term ‘mineral zoning’ refers to the systematic spatial variation in the composition of a single mineral grain. Concentric zonation reflects compositional variations perpendicular to the crystal surfaces, whereas sector From: mineral zoning in The Oxford Companion to the Earth »
What is halite used for?
It is frequently used in food preservation methods across various cultures. Larger pieces can be ground in a salt mill or dusted over food from a shaker as finishing salt. Halite is also often used both residentially and municipally for managing ice.
What type of rock is plagioclase feldspar?
Plagioclase Occurrence Plagioclase feldspar group minerals are the most common rock-forming minerals. They are importantly dominant minerals in most igneous rock. They are major constituents in a wide range of intrusive and extrusive igneous rocks including granite, diorite, gabbro, rhyolite, andesite, and basalt.
What kind of twinning does plagioclase have?
Plagioclase commonly shows this type of twinning, called the Albite Twin Law, with {010} as the twin plane. Such twinning is one of the most diagnostic features of plagioclase.
What is talc used for in everyday life?
Uses of Talc: Talc is used as a filler, coating, pigment, dusting agent, and extender in plastics, ceramics, paint, paper, cosmetics, roofing, rubber and many other products.
What are the three most useful properties for the identification of halite?
Diagnostic Properties Cleavage, solubility, salty taste (The taste test is discouraged.