This is the polished anorthosite specimen with irisation in the blue and yellow-green colors. Dimensions: 4.1 x 1.8 x 0.2″ (10.5 x 4.5 x 0.5cm). Weight – 2oz (58 grams). Origin: Russia, Transbaikalia.
Some information about anorthosite:
Anorthosite is a phaneritic, intrusive igneous rock characterized by a predominance of plagioclase feldspar (90–100%), and a minimal mafic component (0–10%). Pyroxene, ilmenite, magnetite, and olivine are the mafic minerals most commonly present.
Anorthosite on Earth can be divided into two types: Proterozoic anorthosite (also known as massif or massif-type anorthosite) and Archean anorthosite. These two types of anorthosite have different modes of occurrence, appear to be restricted to different periods in Earth’s history, and are thought to have had different origins.
Lunar anorthosites constitute the light-coloured areas of the Moon’s surface and have been the subject of much research.