By Chisom Ibemere
Microcline is one of the igneous rock-forming tectosilicate mineral and a potassium-rich alkali feldspar. It contains small quantity of sodium. It is mostly seen in granite and pegmatites. Its formation occurs during slow cooling of orthoclase and more stable at lower temperatures than orthoclase. It is a clear, white, pale-yellow, brick-red, or green mineral which is typically characterized by cross-hatch twinning that forms as a result of the transformation of monoclinic orthoclase into triclinic microcline.
The name Microcline is gotten from two Greek words micros and Klino which means small and lean respectivy. This is due to the cleavage planes in microcline which deviate very slightly from 90 degrees.
Microcline occurs in varieties of colours such as White, grey, greyish yellow, yellowish, tan, salmon-pink, bluish green, green. It has a Vitreous lustre with a hardness of 6 – 6½, specific gravity of 2.54 – 2.57 and Triclinic crystal system. The stones show no pleochroism.
Microcline occurs in several number of metamorphic rocks. It occurs in granites, granite pegmatites, hydrothermal veins, schists and gneisses. It also occurs as grains in sedimentary rocks.
Microcline has been in existence since the ancient times and appreciated for its beauty throughout history. It has been used by the ancient Egyptians for it’s Jewelry and Ornamental purposes. Microcline is mainly used for the manufactue of porcelain.
Crystals may be seen in places such as Australia, Zimbabwe, Mozambique, Namibia, Canada, Madagascar, and Tanzania.