FMF - Friends of Minerals Forum, discussion and message board

[Dany Mabillard]

Hello everybody,

I need some help to identify this mineral if it is one, found in Mellikon, Argovie, Switzerland.

Thank you in advance for the time you'll take to answer me.

Have a nice day.

Best regards.

[vic rzonca]

Dany, you might try an acid test on a bit of the unknown, possibly scraped from an in-obvious place. Put a few drops of lemon juice on it. If it fizzes, combined with the location, would indicate limestone.

[Michael Shaw]

Dany,

Mindat lists Mellikon as a quarry in Jurassic limestones. My guess is that you will find an acid test yields positive results indicating a carbonate. Your specimen looks to me like a calcite or limestone replacement of coral.

Michael

[SteveB]

Looks like a coated coral, likely fossilised with outer coating of calcite, possibly chalk. The smoothness is unnatural for Coral. But there are indications is not waterworn and crusty cavities I expect you will find tiny crystal growth If you examine under magnification. Examination of the breakage underneath may also help. It may show deposition rings to help out.

[Dany Mabillard]

Thank you Michael, Vic and Steve for your answers. I will do the test and investigations next weekend when I can access the specimen.

Have a nice week.

Dany.

[Riccardo Modanesi]

Hi to everybody!
Yes, I agree with Steve: in my opinion it's a fossil coral. The area is well known both for corals and for ammonites and nautiloids. Some corals DO have this aspect.
Greetings from Italy by Riccardo.

[Dany Mabillard]

Thank you all for your answer. I tried with the lemon in the back where it's like the front without success but maybe I haven't done correctly. In the back, the whiter part seems to be Chalk (1 in the moh's scale). I put 2 photos from the back

Have a nice day.

[vic rzonca]