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Fun Facts Friday: The 3 main types of Rocks!

Fun Facts Friday.......

Along with the rockhound journey, the ability to easily identify the rocks that we find is extremely important. Or at least have a better understanding on how they were formed. There are 3 main types of rocks. Igneous, Sedimentary and Metamorphic. They are broken down into subcategories from there.

Igneous rocks are formed from melted rock deep in the earth's crust. The geological meaning is a rock that has formed from lava or magma. Examples of Igneous rocks are Basalt, Granite and Obsidian.

Sedimentary rocks are formed by layers of decomposition

of mineral or organic substances. Some examples of sedimentary rocks are Sandstone. Limestone and shale.

Metamorphic rocks are formed by ither rocks through pressure or heat. Some examples of metamorphic rocks are Marble, Gneiss and Quartzite.

Most Igneous and Metamorphic rocks carry a hardness of 6 and 7 on the mohs scale. Volcanic rock like Obsidian is about a 5.5 to 6 on the scale. Sedimentary rocks are fairly soft down in the 2, 3 and 4 range. Although chert, which is a sedimentary rock is about a 7. Since it's mostly composed of Quartz. Agates are a little different, they are categorized both the igneous and sedimentary categories, depending on your specimen.

In a future post I will go over the Mohs scale and some examples of how you can guesstimate what kind of stone you have.

I have included some pics below with some examples. Again, I am not an expert, just trying to learn with you. I hope this helps. If anyone would like to chime in with experiences, tips or corrections. Please do. Please feel free to share!

It's a beautiful day to be at the beach!


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