Heteromorphite (Pb7Sb8S19) is an iron black colored member of a series with galena. Its name comes from the greek for “different” and “form” in allusion to a proposed dimorph. Its crystal form is pyramidal in subparallel growths. — Photo: Darla Sondrol · CC0
Heteromorphite
Heteromorphite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula Pb₇Sb₈S₁₉.
It crystallizes in the monoclinic crystal system (space group C2/c).
Key properties: Mohs hardness 2.5–3; specific gravity 5.73; Black streak; Metallic. R1 –R2: n.d luster.
IMA symbol Htm, grandfathered status — known before the IMA’s founding, named in 1849.
Hydrothermal in origin.
It is found associated with Sphalerite, plagionite, semseyite.
Its name comes from the Greek for different and form, in allusion to the difference between this mineral and a proposed dimorphous species.