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Minerals

Do you remember the last time you picked up a pebble? Maybe it was as clear as glass. Minerals formed the colors and patterns in the pebble. A is a solid, nonliving substance that occurs in rocks or in the ground. Every mineral has unique properties. Earth's surface is , a solid substance made of minerals. Rock can be made of many or of one mineral with different-sized grains.

There are more than 4,000 . Many of them look alike. use the minerals' physical properties to tell them apart. For example, scientists can compare the hardness of two minerals by how easily they can be . Gypsum and calcite can look alike, but gypsum is easier to than calcite.

The way a mineral reflects light is its luster. Two minerals may be the same color, but one may have a luster and the other a dull luster.

When you rub a mineral across a surface, the mineral leaves a streak of powder. This colored can help scientist identify two minerals that look alike.

Minerals have other , too. Is the mineral magnetic? What shape are its crystals? minerals might look alike and share some properties, but they don't share all . Gold and pyrite are both shiny and gold in color. Pyrite is sometimes called because people have mistaken it for gold. Gold is much softer than pyrite. Gold leaves a golden streak. Pyrite's is greenish black.

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