Rockhounding

Igneous rocks form when molten rock (magma) cools and solidifies, with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. This magma can be derived from partial melts of pre-existing rocks in either the Earth's mantle or crust. Typically, the melting is caused by one or more of the following processes -- an increase in temperature, a decrease in pressure, or a change in composition. Over 700 types of igneous rocks have been described, most of them formed beneath the surface of the Earth's crust.

Rock formed from sediments covers 75% of the Earth's land area, and includes common types such as chalk, limestone, dolomite, sandstone, and shale.

Sedimentary rocks are classfied by the source of their sediments, and are either: clastic rock formed from fragments broken off from parent rock, by weathering in situ or erosion by water, ice or wind, followed by transportation of sediments, often in suspension, to the place of deposition; biogenic activity; or precipitation from solution.
The sediments are then compacted and converted to rock by the process of lithification.

Metamorphic rock is the result of the transformation of a pre-existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat (greater than 150 degrees Celsius) and extreme pressure causing profound physical and/or chemical change. The protolith may be sedimentary rock, igneous rock or another older metamorphic rock.

Metamorphic rocks make up a large part of the Earth's crust and are classified by texture and by chemical and mineral assemblage (metamorphic facies). They are formed deep beneath the Earth's surface by great stresses from rocks above and high pressures and temperatures. They are also formed by the intrusion of molten rock, called magma, into solid rock and form particularly at the place of contact between the magma and solid rock where the temperatures are high.

The study of metamorphic rocks (now exposed at the Earth's surface following erosion and uplift) provides us with very valuable information about the temperatures and pressures that occur at great depths within the Earth's crust.

Some examples of metamorphic rocks are gneiss, slate, marble and schist.

Rockhounding is a great hobby for both the young and the old. Get your kids or grandkids interested in geodes and minerals and you have something that you'll be able to share for a lifetime. Click on picture for info on Dene's humorous rockhound tees and gifts.

While hopping around the internet searching for good rockhounding sites, I ran across a site called Rockhound Notes. It has a lot of good stuff and if the webmaster ever drops by here, I'd like to say "Good Work"!

But in the meantime, I wanted to add a link to his page that list all of the mining claims in the country. A handy list for any rockhounder!

Click Here to check it out. You'll have to click on the state of your choice to get the list for that state, but it does appear to show them all.

There's also a great page on cleaning minerals!

Thanks for stopping by! Be sure to check out my other lenses when you have time.

Much of the information used here has been researched from Wikipedia, the free encyclopedia.

All text is available under the terms of the GNU Free Documentation License.

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