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.
- Sapphire refers to all gem varieties of Corundum, excluding the red variety of Corundum which is classified as Ruby. In the gem trade, it refers specifically to the blue gem variety of Corundum, unless a color is mentioned as a prefix to sapphire (i.e. Green Sapphire).apphire is also only used to describe the gem variety; otherwise it is simply called Corundum. Corundum is a very hard, tough, and stable mineral. For all practical purposes, it is the hardest mineral after Diamond, making it the second hardest mineral.