Cermikite

Cermikite is not a mineral but a laboratory grown substance (chrome alum). On Ebay listings, one usually has to read the fine print to find this out, if it is mentioned at all. The "locality" mentioned is usually Poland.

Thanks for the warning, Peter. This is a good example of a large class of commonly faked "mineral" specimens, the water soluble crystals. It is easy to dissolve certain water-soluble salts in water and then crystallize them out on a string (as we all did in school) or on a natural rock matrix (as the fakers do). The most common "minerals" faked this way are halite (common table salt), chalcanthite (copper sulphate), and lopezite (potassium chromate).

Chalcanthite and lopezite do occur as natural minerals, but never in large impressive crystals like the ones offered at shows. "Chalcanthite" and "Lopezite" are mineral names, not chemical names; the artificially grown crystals are chemically the same but are not minerals, so it is criminal misrepresentation to use "chalcanthite" and "lopezite" on the labels; dealers should call them by their chemical names "copper sulphate crystals", etc.

As Peter noted, Poland is a common source country for faked water-soluble minerals (along with synthetic "zincite" crystals and variously enhanced and faked amber). (Sorry, Grandma Klimaschevska.) Romania is another frequent source.