Albite 3.90 ct.

Albite

Albite belongs to the Plagioclase Feldspar group, an isomorphous solid solution series. Albite is one end member, containing sodium and no calcium. The other end member, Anorthite, contains calcium and no sodium. The intermediary members are Oligoclase, Andesine, Labradorite, and Bytownite. Oligoclase and Andesine are considered by some to be a variety of Albite rather then a separate mineral. The acclaimed Dana's System of Mineralogy lists these intermediary members as individual minerals, whereas the IMA does not recognize them as individual mineral species.

Albite also forms a series with Sanidine, and the intermediary member of this series is Anorthoclase. Albite can contain up to ten percent potassium replacing the sodium. If more than ten percent replaces the sodium, the mineral is no longer Albite, but Anorthoclase.

Albite is a very common mineral, and is an important rock-forming mineral. It takes a longer time for Albite to crystallize than the other feldspars. This enables Albite to form in large and well crystallized examples. Albite is also a common accessory mineral to many rare and unusual minerals. The iridescent variety Peristerite sometimes exhibits an adularescent sheen. This produces an unusual form of Moonstone.

Albite sometimes forms in association with the feldspar mineral Microcline in alternating patterns, and forms a feldspar rock known as Perthite. (from :Mineral.net)

In the year 2018 has been found a small pocket in Brazil that produced a small quantity of colorless gem quality albite.Generally white albite is opaque or translucent or vitreous,but in small crystals,but here we have a good example of this gem in a good size.

Size: 13.2x9.5x5.5 mm.

Weight: 3.90 ct.

CODE#7563