The Fuka mine in Japan (no mispronunciations, please; the name is pronounced Foo-kah) has yielded a large variety of rare minerals and is the type locality for twelve species, with more to come. It is undoubtedly most famous among collectors for its dark blue henmilite, a calcium and copper borate. (Is it really blue? We'll get to that question later.)
Alfredo Petrov, a consulting editor of Rocks & Minerals, is a geologist and part-time mineral dealer and collecting guide.