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Let's Rock => Identifications of Materials => Topic started by: drnihili on January 11, 2015, 05:55:10 PM

Title: Yard rocks
Post by: drnihili on January 11, 2015, 05:55:10 PM

I finally got the saw set up with the new motor and had a chance to cut some rocks tonight.  I have no clue what either one really is of course, but especially the second.  Guesses and pointers are welcome.

The first doesn't scratch with a good piece of steel on the white, but the black falls to a cheap steak knife.  The second laughed particularly loudly when I tried to scratch it.  Not so much as catching on a divot. The second is slightly greener in person, but a very black green.  It requires a raking light to really see the contrast well, I'm hoping it will do better in sunlight and will post an update if it does.

Title: Re: Yard rocks
Post by: Phishisgroovin on January 11, 2015, 08:25:40 PM

try to cut a slab off that second one to see if its transparent with a bright light behind it?

Title: Re: Yard rocks
Post by: drnihili on January 12, 2015, 07:56:56 AM

The piece with the exposed face is a slab leaned up against the bigger rock.  I can't detect even a hint of translucence. 

Title: Re: Yard rocks
Post by: drnihili on January 12, 2015, 01:00:09 PM

Here's a better shot of the greenish one.  The direction of light makes a lot of difference.  With raking light there's some lovely contrast, with straight on light it looks like a more uniform greenish black.