The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German geologist and mineralogist Friedrich Mohs and is one of several definitions of hardness in materials science.
Seraphinite is a form of clinochlore, a member of the chlorite group. Seraphinite is mined in a limited area of eastern Siberia in Russia. Generally dark green to gray in color, has chatoyancy, and has hardness between 2 and 4 on the Mohs scale.
Alexandrite ( Chrysoberyl ) - BeAl2O4. Mohs scale hardness 8.5 - Lake Manyara, Tanzania. V-twin Alexandrite crystal, gemmy with good crystal form. Chunky floater crystal with no damage or points of attachment. Purple and green color. These were found some time ago and have not been seen since. thumbnail - 1.3 x 1.1 x 0.6 cm
Although this gemstone came into being millions of years ago, it has only been known by the name of morganite since 1911, before that the gemmological world simply viewed the 'pink beryl' as a variety of beryl, not as a gemstone in its own right. mainly comes from deposits in Brazil, Madagascar, Afghanistan and California. Its good hardness of 7.5 to 8 on the Mohs scale
Epidote is a silicate mineral, a calcium aluminum iron silicate. It has a hardness of 6 to 7 on the Mohs scale. One of its distinguishing characteristics is strong pleochroism, where crystals display different colors -- green, brown and yellow -- as they are viewed from varying angles.