Minerals and Their Properties

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Properties of minerals are how scientists classify minerals. The properties are: Luster, color, hardness, streak, cleavage, and crystal shape.

Luster is one of the properties that show how the mineral reflects light. For example, galena has a metallic luster.

Some minerals are different colors. If you see a tan mineral, you can’t assume that it is mica. The color of mica can be tan. Some mica can be black. Color isn’t the best way to identify a mineral.

Scientists use a scale to tell how hard a mineral is. It is called the Mohs Scale. The scale is from 1 to 10. If the mineral is 10, then it is very hard. If it is one, then it is very soft. The talc mineral is soft, so talc cannot scratch diamond which is 10. The mineral that is harder can scratch the softer mineral. The softer mineral cannot scratch the harder one.

Scientists use a streak plate to tell the streak color. The mineral scratches the streak plate, and the mineral leaves a stream of rock powder on the plate.

Cleavage is a pattern that a mineral breaks into. If the mineral breaks into smooth, flat surfaces, then that is cleavage. Some minerals don’t have cleavage at all. Mica breaks into thin, shiny layers that are flat and smooth. Mica has cleavage.

Crystal shape is if the mineral has a shape that stays that way. If you compare two same minerals, they would have to be the same shape if they have crystal shape.

(Tia March 30, 2009)

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