Chamosite ("Thuringite") pseudomorph after Almandine

Item Description

Thuringite is an outdated name for the ferroan variety of Chamosite, a Chlorite Group mineral. Here we have a good sized, sharp, textbook dodecahedral Almandine garnet crystal that has been pseudomorphed by silvery black Chamosite sitting on matrix. The pseudomorph measures 2.7 cm at its longest dimension. This is a classic material from the old iron mines of Marquette County. Rare and excellent historic material. I'm told that this material is also magnetic, but I couldn't get it to react to a magnet here at the office, so maybe it's only slightly magnetic.