Report on changes in mineral specimens.

Hello all,

This is just a report for Phototropic changes in Bulgarian Manganocalcite.I've been said that the Calcite from Madan loses the rose color when exposed to sunlight for a few months.It turns milky to transparent.

Also,Calcite (from these localities,at least...) cracks and cleaves at low temperatures ( I don't know how low exactly,but the temperature in Bulgaria during the winter can reach -20 Ce.

Please report at this topic any similar changes you know of at specimens of a specific locality.

All the best,

-Kostas.

About 30 years ago I left two very nice Viburnum Trend Calcites in my car overnight after a mineral club meeting. It was the middle of winter and somewhat below freezing, perhaps zero F. Both specimens cleaved internally in several places.

I made the same mistake this winter as Ed did, with a large amethyst crystal. Tiny salt crystals formed along the outside of the crack, so the damage was presumably caused by the freezing of a liquid saline inclusion.