Picked up a chunk of basalt near Mt. Hood last spring that had a weird green streak

Turns out it was olivine weathering out, and I spent an hour trying to scratch it with my pocketknife before realizing it was harder than my blade. Has anyone else been fooled by a mineral that looked softer than it actually was?

2 comments

2 Comments

emerycarr6d ago

Picked up a chunk of basalt near Mt. Hood" - oh man, I felt that. I did the exact same thing with a piece of jasper I found in a creek bed last summer. It looked so soft and chalky, I figured I could scratch it with my thumbnail no problem. Nope. Spent ten minutes digging at it like an idiot before I realized it was harder than my knife too. Those green streaks always get me though, especially olivine. I swear every time I see that color my brain just assumes it's something soft like serpentine or a weathered clay. Good reminder that looks can be totally deceiving with rocks.

jessica_miller6d ago

Tell me about it. Got fooled by a piece of chert that looked like dried mud once. Learned my lesson the hard way too.