Some horses, especially older horses that are very relaxed, let their lower lip droop markedly. This is usually a normal finding. When these horses become more stimulated, the appearance changes. The key to this is that the appearance is symmetrical on left and right sides.
Because of corundum's hardness (pure corundum is defined to have 9.0 Mohs), it can scratch almost every other mineral. It is commonly used as an abrasive on everything from sandpaper to large machines used in machining metals, plastics, and wood.orundum from Brazil, size about 2 cm Ã 3 cm (0.8 in Ã 1 in). Corundum occurs as a mineral in mica schist, gneiss, and some marbles in metamorphic terranes. It also occurs in low silica igneous syenite and nepheline syenite intrusives.
Richard Kirwan used the current spelling corundum in 1794. Known by many names in ancient times: adamant, sapphire, ruby, hyacinthos, asteria, etc. The aluminum analogue of Eskolaite, Hematite, and Karelianite. The red (Cr-bearing) gem variety is called Ruby. The blue (Fe- and Ti-bearing) gem variety is called Sapphire. Visit gemdat.org for gemological information about Corundum.