FMF - Friends of Minerals Forum, discussion and message board

[Bob Carnein]

I am seeing specimens of purple aragonite "stars" on eBay, that consist of thin, tabular, twinned purple aragonite "crystals" from Spain. These look, to me, like acid-etched slabs of larger twinned crystals. Does anyone know whether they're indeed man-modified? My apologies if this topic has been discussed before; I'm still learning the organization of the FMF site.

[John S. White]

There is a dealer, saw him in Munich last year, who is selling twinned aragonites from Spain that are acid dipped. He readily acknowledges that, but you have to ask, he does not volunteer that information. He had flats and flats of them and the flat price was very attractive, in other words cheap. They are very attractive because they have a nice shiny surface and the acid treatment deepens the color.

[Jordi Fabre]

Good info in the Spanish side: https://www.foro-minerales.com/forum/viewtopic.php?t=12675 (you can use the Google translator located at the top left of every page)

[James Catmur]

Summary: "they have been treated with acid"

[Bob Carnein]

Thanks, all, for confirming this.