I have previously sold this occurence Tangdanite as Clinotyrolite, which has been discredited as being the same as Tangdanite. Mindat also states: "Unique combination of elements (the only Ca-Cu arsenate-sulphate mineral known)."
The crystals are stunning in-hand and even more so under the microscope. These are flat-lying to about 2mm across. Some of crystals are free-standing.
