The vinegar test that made carbonate rocks click for me

When I first worked with sedimentary rocks, calcite and dolomite looked the same to me. I spent hours comparing textbook pictures to my samples with no luck. A field assistant saw my struggle and handed me a tiny bottle of plain vinegar. She explained that a drop on calcite makes it fizz, but dolomite stays quiet. I tried it on all my samples, and suddenly it made sense. These days, I can spot the difference from across an outcrop. It is funny how a simple thing from the kitchen gave me a new way to work.

3 comments

3 Comments

finleywilliams6d ago

So does the vinegar trick ever give you a false reading? Like on a really weathered, powdery surface of a dolomite, or if the sample is super cold? I've had weak acid react weirdly before.

nancy_thomas486d ago

Ever wonder if grinding the rock into a powder changes how it reacts? Like, would a fine dolomite powder ever fizz a little and trick you?

bennett.jana5d ago

Honestly, watching geologists overthink a kitchen hack is the best part. Sure, if you turn the dolomite into flour or freeze it solid, maybe it'll confuse the vinegar. But at that point, you're just making a rock smoothie for no reason.