My vinegar test on a 'quartz' sample from a yard sale went totally wrong

I bought a pretty clear crystal for five bucks at a yard sale in Spokane, labeled as quartz. I decided to do the classic vinegar acid test at home to check for calcite. I put a drop on it and it didn't just fizz a little, it started bubbling like crazy and left a big white mark! Turns out it was probably a piece of calcite or something else entirely. I learned you really need to be careful with even mild acids on unknown samples. Has anyone else had a simple test completely change what they thought a rock was?

3 comments

3 Comments

sarahbailey21d ago

Remember that vinegar test can also mess with the finish on some fake or treated stones. I saw a guy online try it on a dyed agate and it stripped the color right off, looked awful. Sometimes the test itself leaves a bigger mark than the rock's real makeup.

brown.gavin21d ago

Watched that same video, it was dyed quartz not agate.

bettyfox21d ago

Wow, I used to think that vinegar test was totally safe. Figured it was just a little kitchen science. Saw a piece get ruined like yours, big white crusty spot. Totally changed how I handle my own finds now. I don't even touch them with water until I'm way more sure. That mild acid is no joke on the wrong stuff.