My buddy said my rock ID was all about color, and he was totally right

I was showing off a piece of granite I found near Boulder, calling it 'pink granite' because of the feldspar. My friend, who's a geology student, just looked at it and said, 'Derek, you're just naming colors. What about the texture and the actual mineral grains?' He was right. I was skipping the real stuff. So now, I carry a cheap 10x hand lens and a steel nail for a hardness test. Last weekend, I found a dark rock and instead of calling it 'black rock,' I checked. It scratched glass, had no cleavage, and was fine-grained. Turns out it was basalt. It's way more fun to actually figure it out than just guess. What's one simple test you always do first when you find a new rock?

3 comments

3 Comments

kevinc8410d agoMost Upvoted

That hand lens move is a total game changer, I did the same thing last year. My first test is always the streak plate because color lies so much. A red rock can give a yellow streak and completely change the ID, it's wild.

leerobinson10d ago

Remember when streak plates were just a weird ceramic tile?

-1

taylor.paige7d agoTop Commenter

Yeah, that shift from just looking to actually testing is huge, like @kevinc84 said about streak. I was the same way, just going by color for ages. Getting a hand lens made me slow down and actually see the grains, which changes everything. It feels way more solid when you have a few simple checks to go on.