Corderoite is a very rare mercury chloride sulfide and this excellent layered specimen is from the Type Locality - the McDermitt (Cordero) Mine of Nevada. This is very rich mercury ore. Dark red bands of microcrystalline to massive cinnabar alternate with layers of tan limonite. The corderoite is the rich dusting of the yellow-tan microcrystals found on all sides of the specimen and on both the cinnabar and limonite. Corderoite was not named until 1974, but primary mercury production of this small mine was over before 1941. This material probably dates to that time. From an old European collection.