What are the actual black rocks made of?

HughMungus · Post by **HughMungus** » Thu Sep 09, 2004 10:23 am

I picked up some rocks off the playa. They're black and look igneous. I think they're basalt. Anyone know for sure and know what I need to drill a hole in these things?

TIA

Badger · Post by **Badger** » Thu Sep 09, 2004 11:05 am

I picked up some rocks off the playa. They're black and look igneous. I think they're basalt. Anyone know for sure and know what I need to drill a hole in these things?

Andesite.

The Black Rock for which the desert is named is a remnant piece of an island arc that docked with what was once the western edge of the continent about 375 million years ago. Geologists have named the arc Sonomia http://geology.wcedu.pima.edu/~rvaldez/sonomia.html. A contemporaneous example being Taiwan which is slowly heading towards the mainland of China. Eventually the island will be subducted into a trench not far off of the coast but a remnant pieces will eventually be scraped off or 'docked' in what is known as an accretionary wedge.

sparkletarte · Post by **sparkletarte** » Thu Sep 09, 2004 1:35 pm

I got one of these rocks that someone left in our lounge- thank you whoever did that!

I remember someone at the Meet & Greet said they polish them to bring back every year? Was that you Unjon? If so, thanks for the (in)direct gift!

unjonharley · Post by **unjonharley** » Thu Sep 09, 2004 3:21 pm

Those rock are damn hard to drill. Will be trieing some glues and maybe knot tieing/weaving this next year. I want to know what the green is inside some of the black rock. I found several gravel size with exposed green stone inside.

If you take a stone from BRC you must bring t back for a visit once a year. They do get lonely you know.

Badger · Post by **Badger** » Thu Sep 09, 2004 3:43 pm

The green is most likely serpentine (sepentenite). The andesite is fairly hard stuff (around 7 on the mohs hardness scale). Try a carbide tipped drill bit if you have to drill into the stuff.

amazon · Post by **amazon** » Tue Sep 28, 2004 7:14 am

the black rocks I found look more like basalt than anything else...

Badger · Post by **Badger** » Tue Sep 28, 2004 8:50 am

the black rocks I found look more like basalt than anything else...

Andesite and basalt originate from the same source. Chemical compounds are different mostly in the ratios between the two. Basalt is usually related to underwater injection where it cools relatively quickly. Andesite is usually emplaced into the crust where it has a longer time to cool which allows crystallization to take place which in turns makes the rock much harder.

Bob · Post by **Bob** » Tue Sep 28, 2004 11:20 am

I think what you found were sexstones.

IE, they're just fucking rocks.

BAS · Post by **BAS** » Wed Oct 13, 2004 5:54 pm

Fucking rocks? You'd need a pretty wide drill bit to do that!

)'(Rawhide · Post by **)'(Rawhide** » Sat Oct 30, 2004 7:46 pm

Badger wrote:The green is most likely serpentine (sepentenite). The andesite is fairly hard stuff (around 7 on the mohs hardness scale). Try a carbide tipped drill bit if you have to drill into the stuff.

Hey Badger.....what about Olivine? I've been doing some research online and olivine is often found in volcanic rocks (including andesite). I'm fascinated with geology lately, especially after visiting yellowstone after the burn this year where i found some incredible chunks of obsidian. Anyway, I'm just trying to get to the bottom of the green........

Rawhide

Badger · Post by **Badger** » Sun Oct 31, 2004 10:19 am

Olivine is indeed a possibility - especially since it gets generated under ultra mafic conditions - the same as andesite generally speaking. If the green in the particles in question have more of a crystalline appearance I'd probably go with that.

What are the actual black rocks made of?

What are the actual black rocks made of?

~

the green in the black.....