Crystal shape

Minerals are sometimes found as well formed crystals. The shape of these crystals can often be used to identify minerals.

Each crystal is a solid shape. The flat faces of these crystals can be squares, rectangles, triangles, diamonds or hexagons. When you look at a mineral you may recognise these familiar shapes.

Pyrite sometimes crystallises to form perfect cubes. Cubes have six square faces. They look like the dice you use to play a board game.

Pyrite crystals are cubes

Quartz is often found as long pointed crystals. If you were to slice through one of these crystals, you would see a shape called a hexagon. Hexagons have six sides. A quartz crystal is made up of a hexagonal prism, topped by a hexagonal pyramid.

Quartz crystals are hexagonal

Sometimes it is difficult to see the shape of the crystal clearly - they may be just too small. If you do have a large enough crystal, try and find the basic shapes that make it up. Are its faces square, rectangular, or triangular? Can you see prisms or pyramids?

If you can get some idea of the shape of a crystal, it can help to identify a mineral.

Ernest the mineral detective To find out about minerals you should Take a closer look, and then find out about some of their properties...

Colour Light
Lustre Streak
Crystal shape Hardness
Cleavage and fracture Heaviness
Other tests What we have learnt

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