An unusual AugiteThe pyroxene family is a large one, including well known gem varieties such as Jade

An unusual AugiteThe pyroxene family is a large one, including well known gem varieties such as Jadeite and Bronzite but also less common ones such as the deep olive green Jeffersonite in the photos. These minerals crystallise from lavas, usually towards the silica poor end of the spectrum (with the exception of metamorphic Jadeite) and incorporate a variety of metals in their silicate structure, in this case zinc, manganese and iron. Brown specimens also exist.It was named after the American president and scientist in 1822, having been discovered in the Franklin mining area of New Jersey (seehttp://bit.ly/2EFuEf0 and http://bit.ly/2CqRjJy), who sent a grateful letter of acknowledgement for the specimen that he was sent. It grows in pegmatites, the last slow cooling remnants of cooling magmas, and can grow up to 30cm long, though the specimen here depicted is only 11.0 x 6.3 x 4.3 cm. it often forms in skarns as well, those products of stewed limestone that has been baked by intruding magmas as they cool and spit hot mineralised fluids into the surrounding country rocks. Alongside the type locality in the USA it is also found in South Australia and Sweden, though the current piece comes from New Jersey.LozImage credit: Rob Lavinsky/iRocks.comhttps://www.mindat.org/min-2085.html -- source link

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