Mineral Mondays #70 - Obsidian & Road Trip To The Utah Desert Finale

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Unless you've been living under a non-volcanic rock, you've probably heard of obsidian. Popularized by Minecraft the past 15 years, obsidian is volcanic glass. Have lava, add water, wallah, you can make obsidian swords! While sharp, obsidian isn't a good idea for a combat weapon.

Two weekends ago I was up in Utah digging for rare minerals, topaz, red beryl, opal, etc. One of the less rare, but still collectable minerals I was seeking was obsidian.

As I mentioned, obsidian is volcanic glass. It forms during rapid cooling in magma that is made up of lighter minerals, mainly silica. This fast cooling doesn't allow mineral crystals to form, instead forming a glass.

There are several types of obsidian, but I am going to focus on 4 that can be found in Utah, Apache Tears, Snowflake, Mahogany, and plain obsidian.

Apache Tears are small, ball like obsidian ranging in size from a few millimeters to several centimeters. They occur when an eruption happens during very cold weather, rain, snow or when the lava impacts water.

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Snowflake obsidian is obsidian with cristobalite inclusions.

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Mahogany obsidian is my favorite variation. It has brown inclusions from iron inclusions that contrast nicely with the black obsidian.

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And good ole' plain obsidian.

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Apache Tears can be found in between Spor Mountain and Toapz Mountain on Fluorspar Road. The road & washes are loaded with the glass so collecting them is as easy as opening your car door and picking them up. The zone begins as soon as Brush Beryllium Road turns into Fluorspar Road.

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The three other varieties are found about 2hours south of Topaz Mountain off Kanosh Road. This is a dirt road that connects two main highways, the 257 & 15. Honestly, some of Utah's dirt roads are better than Los Angeles roads!

Even though this locality is large and filled with obsidian, it is difficult to find unless you have GPS coordinates so here they are: Long - 112° 49' 54.57" W, Lat. 38° 46' 6.12" N.
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The obsidian here runs in large veins and caps.

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The hill I was on was covered in veins and large masses or caps. Both the mahogany & snowflake occurred near each other, several feet apart, but not together. The hillside was littered with obsidian that had fractured off the veins and caps from above. The material was very brittle though so getting large pieces was impossible. They would just break up as soon as you pick them up. Still, it was easy to get pieces from 2-8 centimeters.

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There is something beautiful about the silence & bleakness of the landscape.

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The snowflake material I found had very small cristobalite inclusions and is translucent!

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It looks much cooler in person.

I didn't find too much of either snowflake or mahogany, but enough to make me happy.

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After about an hour of hunting I had enough and decided to head out. However, only a quarter of the day was done. I still had to head down to my magnetite collecting spot down in Cedar City.

The road out of the obsidian collecting location.

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Just over 1 hour later I arrived at the Blackbird Mine, an open pit iron mine. This mine produces beautiful magnetite, apatite & siderite specimens.

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Quick side note, this mine is located along the old Spanish Trail. It's pretty incredible to know the Spanish made it all the way up here on horseback from Mexico & Central America.

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The weather was awesome so I spent the next few hours easily digging into the massive iron vein and other spots in the pit.

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Large crystals when cleaned up with water and a wire brush will shine metallic.

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A great example of a vein large enough to allow crystals to grow in.

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Magnetite & calcite & apatite

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Occasionally you can find amethyst vugs can be found, but they are usually deep in the iron and very hard to break out.

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I finished up at about 2pm and decided if I left then I could make it back to Orange County, CA by about 9pm so I bolted to In & Out for a late lunch in St. George and headed home.

One last look at the beautiful clouds and landscape until next time.

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It was another fantastic trip to Utah, one of my best for mineral collecting. If gas isn't so expensive I'll head back up in the fall. Maybe even stop by to say hi to @enforcer48. Anyone else in Utah? Maybe we could all meet up, out in the middle of the desert!

My two previous posts about this trip:

Road Trip To Utah P1
Road Trip To Utah P2

Thanks for reading!

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