Diorite
"Diorite is
sometimes called 'black granite'."
It is an intrusive igneous rock, which is formed mostly along the margins of continents. It can be formed in large intrusions, or smaller ones such as sills and dikes.
It is a rock similar to granite, however it is darker in colour.
It contains some quartz and feldspar - light-coloured minerals, but much less than do granitoids. Instead, it contains a fair bit of dark-coloured minerals such as biotite and hornblende.
It is much rarer than granitoids, and it tends to have smaller grain size. It is also similar to gabbro, however its plagioclase is sodium-rich, while the plagioclase of gabbro is rich in calcium.
If the magma with the same composition forms an extrusive igneous rock, it will be andesite.
This rock was used in the ancient Egypt to carve sculptures and build pyramids.
By francmaleckar
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