Thread: Trying to identify old hone. Help appreciated!

Uhhh. Arks are damn near 100% microcrystalline silica. The closest stone found in nature to 100% silica. Usually something like 99.9% IIRC. They are not quartzite, that is a different animal, though quartzite can have a similar composition, characteristics and level of silica (not quite as high though). JNats are mostly way softer (yes there are exceptions, but pretty much ALL Arks are hard as a coffin nail) and with smaller percentage of silica (IIRC somewhere around high 60's% to low 70's%) but having more other things like alumina, mica, iron oxides, clays and others.