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Thuringite is an outdated name for the ferroan variety of Chamosite, a Chlorite Group mineral.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 pair of good sized, sharp, fairly lustrous, textbook dodecahedral Almandine garnet crystals that have been pseudomorphed by silvery black Chamosite sitting on matrix. The largest pseudomorph measures 2.0 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.