Amethyst was used as a gemstone by the ancient Egyptians and was largely employed in antiquity for intaglios. Beads of amethyst are found in Anglo-Saxon graves in England. It is a widely distributed mineral,...
Rhodonite is a manganese inosilicate, (Mn,Fe,Mg,Ca)SiO3 and member of the pyroxene group of minerals, crystallizing in the triclinic system. It commonly occurs as cleavable to compact masses with a rose-red...