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[Brokenstone]

This one is a domestic method of cleanliness of calcites that has given an excellent result to me.
To clean the dirt incrusted on a stalactite of white dolomite, on which we have a crystal of calcite (photo sees 1) we will proceed first to a wash with water and a neutral soap, will rub superficially with a toothbrush, will not be too tight too loudly not to damage possible secret crystals under the dirt.
After this, we will allow that it should dry off and will proceed to verify by means of a magnifying glass the advance of the cleanliness, detecting associate minerals that could suffer damage with any process of later cleanliness.
In this case especially, I had detected some small crystals of calcite in the center of the dolomite, beside the crystal discovered at sight scalenohedron that was finishing the stalactite. I did not find more associate minerals. The second part of the cleanliness was a bath of vinegar (acetic acid) for 48 hours, in order not to damage the calcites. To rub again with the toothbrush after this time and to wait for results, we will verify that the cap of dark gray color that on the dolomite is becoming detached leaving to the overdraft the white sheen of this one. The crystals of calcite meet free of organic remains and dirt without suffering any damage. The final crystal is orange, since the second cap of calcita has grown on it, making it more opaque. As like can to observe (photo to see 2) the result is very good and we have not had to use stronger acids (with the risks for the health that this supposes) or expensive machines of cleanliness for ultrasounds.
I hope that this small council could facilitate to you the cleanliness of your samples.
A greeting.
Pablo