Mineral Identification Using Properties To Tell Them Apart

Each mineral has its own properties that can be used to identify it. Hardness Color Streak Luster Density Cleavage and Fracture Chemical activity Special properties

Properties Hardness Color Minerals can scratch any mineral softer then itself and can only be scratched by that of a mineral harder than it. Moh’s scale of hardness ranks minerals from 1 to 10 in order of increasing hardness. Color Can only be used to identify those minerals that have their own characteristic color.

Properties Streak Luster Created when a mineral is rubbed against a hard rough tile that causes it to leave a powder behind Different minerals leave different color streaks The color of the mineral does not always match its streak Luster Term used to describe how a mineral reflects light from its surface Terms to describe luster are glassy, earthy, waxy and pearly, metalic

Properties Density Crystal shape Density is the mass of a sample divided by its volume. In mineral identification density is also called specific gravity. Crystal shape Crystals grow atom by atom. There are six crystal shapes.

Properties Cleavage and Fracture Cleavage is when a mineral splits along flat surfaces. Fracture is when the mineral does not split evenly but forms a rough surface. Tell the students that we will not be breaking any minerals to observe cleave. It is sometime difficult to tell the difference between crystal shape and cleavage unless you break the sample yourself. In some cases the crystal shapes and the cleavage are identical. Halite is one example. You can allow students to look at salt under a microscope to see that it has the same shape as the large halite sample in our set. Quartz on the other hand grows in beautiful crystal shapes.

Quartz Crystal Cleavage

Halite Crystal Shape Cleavage shape

Properties Chemical activity Some minerals react to acid. Mostly the carbonate minerals. Tell the students that we will not be breaking any minerals to observe cleave. It is sometime difficult to tell the difference between crystal shape and cleavage unless you break the sample yourself. In some cases the crystal shapes and the cleavage are identical. Halite is one example. You can allow students to look at salt under a microscope to see that it has the same shape as the large halite sample in our set. Quartz on the other hand grows in beautiful crystal shapes.

Reacting to Acid

Properties Special properties Some minerals glow under ultraviolet light Some minerals give off radiation Some minerals even have electric properties A few minerals are attracted to magnets

Under Natural Light

Under UV light