Pyrite (FeS₂) in its microcrystalline varieties is known for its lack of stability, resulting in pyrite disease. The special composite structure of the variety framboidal-pyrite is demonstrated from micrographs, as are the peculiar, interesting organic membranes (micrographs), generally enveloping the framboids and their constituent microcrystallites. During humid conditions, the pyrite mineral and the carbonaceous matter of the membranes react electrochemically together as electrodes in a galvanic environment. Currently, the only known effective precaution against this is a low relative humidity (constant 55%).