Oklah🌎ma Red Granite EarthCache

Welcome to Stillwater. "Where Oklahoma Began." This earthcache will give you a look into Oklahoma Red Granite including its formation, colors, mineral makeup, and difference in crystal sizes.

Additional waypoints listed with this geocache will take you to other examples around town of Oklahoma Red Granite.

This and other pieces of Oklahoma Red Granite around Stillwater comes from Granite, Oklahoma. It is mined from the Headquarters Mountain within the Oklahoma range of the Witchita Mountains in southwest Oklahoma. 

Composition & Colors: Granite is one of the hardest types of rock and is crystaline in nature. It is made up mostly of quartz and feldspar which are the lighter colors, the whites and the pinks, that you see when you look at a piece of granite. But, it does comes in a wide variety of colors--greens, whites, browns, yellows, blues, blacks, reds, grays, and more. The minerals prevalent in the specific area of the world and the depth it is mined from determine this variety of color. The relative proportion of the different colored minerals in a granite is largely due to the original source of molten rock that cooled to form the granite. Thus classic granite has a "salt-and-pepper" look. The most common accessory minerals are the black mica biotite and sometimes black amphibole hornblende.

So if the molten rock was abundant in potassium feldspar, the granite is more likely to take on a pink color, and if the molten rock was abundant in quartz and minerals that make up amphibole you will likely get a black and white speckled granite. This also means that Oklahoma Red Granite gets its color from potassium feldspar and not Oklahoma red clay which is a common misconception. 

Texture & Crystal size: Granite is an intrusive igneous rock that begins as a molten liquid state that solidifies as it cools. The texture is now determined by the rate at which it cooled. The large mineral crystals in granite are evidence that it cooled slowly from molten rock. That slow cooling occurred beneath the earth's surface and required a long period of time. Granite which cools closer to the earth's surface as when it is exposed to air or water, cools more rapidly and the result is a granite with crystals that are smaller. The image below shows the different size crystals and these will vary in each piece of granite depending on how it was formed. 

The Oklahoma Red Granite you will see at the monument site is considered to have medium size crystals. While in the same mountain region of Oklahoma, the Rose Quarry on the north side of the mountains has much smaller crystals in the granite mined there.

Mining Granite: Granite is found close to the surface, meaning it can be cut from shallow quarries.Much of the Oklahoma Red Graite is actually cut from the mountain sides in Southwest Oklahoma. Small holes are drilled to get the shape of the desired block size (making it easier to transport). Explosives are placed into these holes to carefully create a blast that’s just strong enough to separate the granite from the bedrock, without breaking the block itself.

If you look at the larger piece at the south end by the side walk and a few of the other raw pieces you can see where the holes would have been drilled to place explosives for mining. 

Logging requirements:

Send a geocaching message or email  with the answers to the questions below. Found It logs without the required information sent within 7 days of logging will be deleted. Do NOT post any answers in your found It log. 

1. Based on the cache page information and your observations, Does the crystal size indicate that this cooled slowly or more rapidly?

2. What is your best estimate to the size of the crystals. (example: crystals the size of a pea, fingertip, fly, pencil point - be creative)

3. How many engraved monuments either very large or smaller are at or around this area and what foreign city is referenced on one of them? 

4. Based on the mineral color chart above and your observations, what minerals do you think make up this granite?

5. Surrounding the engraved monuments are several raw pieces of Oklahoma Red Granite (rough, uncut and unpolished). How many of these raw pieces do you see? (NOTE - some are very large while others are smaller & placed very close to each other - Count Carefully)

6. With your log post a photo of you, your group or geocaching item to show you actually visited the location. (be sure not to reveal any answers in your photo)

Thank you for visiting this earthcache. 

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