Sciencemadness Discussion Board

Mystery rock?

Booze - 15-5-2017 at 16:57

So I got some rocks from my grandfather that we found in crecent lake, oregon. I took a small sample and put it in some HCL, expecting a green color due to it being a red rock. Suprisingly, it turned orange. Any clue what this rock is? I really hope it is cinnabar.

Amos - 15-5-2017 at 17:58

Most likely small amounts of iron(III). Pretty commonplace for rocks I've tried putting in hydrochloric acid. I believe cinnabar is usually pretty inert to acids, and if it did dissolve you'd be more likely to encounter a colorless solution and the release of putrid-smelling hydrogen sulfide gas.

Booze - 16-5-2017 at 05:25

Quote: Originally posted by Amos  
Most likely small amounts of iron(III). Pretty commonplace for rocks I've tried putting in hydrochloric acid. I believe cinnabar is usually pretty inert to acids, and if it did dissolve you'd be more likely to encounter a colorless solution and the release of putrid-smelling hydrogen sulfide gas.


Oh well. Now I just need to precipitate the stuff.