Rocks are made of one or more minerals, they are a rock's raw materials. Like rocks, minerals can be identified by their properties or characteristics. Here are a few things about the properties of minerals that make identifying minerals fun.
Color is the easiest mineral property to observe but it is the least helpful in identifying minerals. Some minerals change color when exposed to moisture, heat or air. Some minerals change color when another mineral is present.
Streak, the tint of mineral's powder, is a more effective way of identifying minerals than color because a mineral's streak never changes shade. To determine the streak of a mineral rub it across a hard surface or streak plate as you would with chalk or crayons.
Luster is the way light reflects on a mineral surfaces. A mineral's luster is either metallic or non-metallic and can be described as dull, waxy, greasy, glassy, pearly, silky and even resinous.
A mineral's specific gravity or heft is its density compared to water. Specific gravity can be measured or estimated. To estimate specific gravity, fill one bucket with water and another bucket of the same size with a mineral. Which one weighs more?
Crystal habit, the shape of a crystal, it is often sufficient to identify a mineral as some minerals have only one form. But crystal habit can also be misleading. If a crystal doesn't have sufficient room to grow its three-dimensional, geometric pattern may not be properly shaped.
Cleavage and fracture describe how minerals break. A fracture is an irregular break that creates a jagged or splintery surface. Cleavage is a clean break that is smooth and flat.
Hardness is a mineral's resistance to scratching. The Mohs Scale of Hardness, named after the 19th century scientist Fredrich Mohs, is used by scientists to rate a mineral's hardness on a scale of 1 to 10.
