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
Universalmuseum Joanneum collection traces its origin to the private collection of Archduke Johann, which encompassed several thousand pieces at that time. Today the inventory has grown to about 80,000 specimens. The collection presents minerals from across the world as well as a Styrian regional collection. The mineralogy department of the Joanneum was where Friedrich Mohs developed the Mohs scale of mineral hardness which remains authoritative. He was the first curator of the Joanneum. Schloss Eggenberg was added to the registry of the Graz Old Town as a UNESCO World Heritage Site in 2010. Schloss Eggenberg is the most significant palace ensemble in