Mineralogy classified into density (often given as specific gravity); measures of mechanical cohesion (hardness, tenacity, cleavage, fracture, parting); macroscopic visual properties (luster, color, streak, luminescence, diaphaneity); magnetic and electric properties; radioactivity and solubility in hydrogen chloride (). "Hardness" is determined by comparison with other minerals. In the Mohs scale, a standard set of minerals are numbered in order of increasing hardness from 1 (talc) to 10 (diamond). A harder mineral will scratch a softer, so an unknown mineral can be placed in this scale by which minerals it scratches and which scratch it. A few minerals such as calcite and kyanite
Emerald Lingam Emerald Lingam Emerald Lingams are established in many Hindu Temples in Tamil nadu. Emerald (Tamil: மரகதம்)is a variety of the mineral beryl (BeAl(SiO)) colored green by trace amounts of chromium and sometimes vanadium. The hardness of Beryl is 7.5–8 on the 10 point Mohs scale of mineral hardness. The toughness (resistance to breakage)of Emerald is classified as generally poor, hence most emeralds are highly included. Emerald is a green gemstone. Emerald means the shade of green color. Because of its green color, the term Emerald is employed. Emerald is also associated with the eighth planet Mercury in the Solar System.