DUMORTIERITE
Dumortierite is best known in its massive form, which makes an attractive violet and blue decorative stone when polished. Prosmatic crystals larger then 1mm are very rare. Dumortierite is also found intergrown with rock crystal and is then called dumortierite quartz. Dumortierite ws named after the French scientist, M.E. Dumortier. An alternative name for dumortierite is "denim lapis".
Hardness: 8.5