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Ever hear of basalt? It’s an igneous rock that forms from lava. It cools
so quickly that it doesn’t have time to form
crystals
.
Granite is an igneous rock, too. But it looks totally different. It has
lots of little crystals inside. They may be gray, white, pink, and black.
Why does granite have crystals? Because the magma it’s made of
didn’t blast out onto Earth’s surface. It might have been stuck at the
top of the mantle. Or maybe it was trapped inside the crust. The
magma cooled slowly. And it formed igneous rock full of crystals.
Some igneous rocks contain big, beautiful crystals. Diamonds
can form inside kimberlite.
Sapphires and rubies can be
found inside pegamite. These
valuable crystals grow slowly
over thousands—or even
millions—of years.
Granite
Cool as a Crystal
