In Limestone article, we learned how sedimentation occurs, and the formation of sedimentary rocks takes place.

Today, we are going to know Obsidian rock, which falls in the main class igneous rocks.

Rarely found colors of Obsidian rocks are:

A very rare occurrence of obsidians is in Blue, Orange, Red, and Yellow.

It also means obsidian is easy to scratch.

The density of rock used to expresses as specific gravity, and it is measured in relevance to the density of water in gram per cubic centimeter of the mass.

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