Lesson 03 Minerals Around Me



Image result for opal mine spencer idahoI went and walked around for a couple hours around Rexburg and couldn't really identify any minerals, so I decided to go back to my roots.I'm from a little town called Dubois. Not too far north is an opal mine in Spencer, Idaho. 

Opal is a silicate mineral and can form in all rock environments, especially in igneous environments. It is a precious gemstone and can be quite expensive to buy. It can be identified by it's luster, streak, and darkening in heat.


Image result for opal spencer idaho
Here are some facts about opal:
Chemical composition: SiO2·nH2O.
Color: colorless, white, yellow, red, orange, green, brown, black, blue, pink
Streak: white
Luster: subvitreous to waxy
Hardness: 5.5-6
Specific Gravity: 2.15
Fracture: conchoidal to uneven
Cleavage: none
Diagnostic Feature: darkens upon heating
Image result for opal spencer idahoThe cool thing about this opal mine is that the public can go mine for just $15. You can stay as long as you like and can bring out a pound of rocks. I've seen some pretty cool opal from there as well as other interesting minerals and rocks. 
I don't have an opal from there, but here are some pictures of what it looks like before and after polishing. 
Overall, it's a really neat place to visit to learn more about minerals and get some hands on experience identifying rocks and minerals.

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