They are the group of
minerals in which sulphur is the anion.
The cation is
often a metal, and these minerals are consequently often valuable metal
sphalerite, galena, chalcopyrite, pyrite, bornite, covellite,
pyrrhotite, marcasite, arsenopyrite, cinnabar and molybdenite.
Sphalerite by Ian Geoffrey Stimpson via Flickr
Sphalerite is a zinc sulphide
- one of the most important zinc ores, because zinc is not found as a native
It is often dark grey but can also be brown, greenish, yellowish and
even white. It is often botroydal, granular or massive in habit. It
forms in hydrothermal veins and is associated to quartz, galena,
pyrite, barite, fluorite and dolomite.
Galena is a lead sulphide.
like zinc, lead is not found as a native element, and galena is one of
the most important lead ores. It is metallic, lead-grey, and can form
many different types of crystals, or be fibrous, granular or massive.
Like sphalerite, it forms in hydrothermal veins and can be found in
association with quartz, pyrite, sphalerite, calcite and/or fluorite.
is a copper sulphide
and an important ore of copper, even though copper also occurs as a
native element. It is metallic, yellower than copper, and can either
form crystals or be massive, compact or botryoidal. Like many other
minerals in this group, it forms in hydrothermal veins and can be found
with quartz, calcite; and other sulphide minerals.
peacock ore thanks
to its peacock-like colouring, bornite is another copper sulphide. It
has the copper-like red or pink colour when fresh, but tarnishes to the
peacock-mix of purple, blue and green. It is formed in hydrothermal
veins and can be associated to quartz, galena and chalcopyrite.
Covellite. By Ian Geoffrey Stimpson via Flickr.com
also a copper sulphide
however it can only be a minor ore in some localities. It is
distinctive purple and indigo-blue in colour, and can occur as
crystals, but is most often massive. It forms when bornite,
chalcopyrite and other copper minerals alter, and can consequently be
found in oxidised copper veins.
Pyrrhotite. By Ian Geoffrey Stimpson via Flickr
an iron sulfide,
however no iron minerals on this page make good iron ores - iron is
instead extracted from magnetite, hematite, and BIF (banded iron
formations). Pyrrhotite is nevertheless
the most common magnetic mineral after magnetite, showing it contains a
fair bit of iron. It is a widespread mineral that can occur in many
different types of rocks.
Marcasite. By Kathy__ via Flickr.com
another one of iron sulfides,
known for its chemical composition identical to the more common
pyrite. The two can however easily be distinguished since marcasite's
crystals are orthorhombic while pyrite's are cubic. They are also paler
and more silvery yellow while pyrite is more brassy yellow in
another iron sulfide
nickname "fool's gold" comes from its golden colour. It is,
however, much lighter than gold, and it gives off sparks when hit by
iron (it can also decay in your collection giving off so much heat that
it can light a fire so watch your pyrite).
It is a common mineral in hydrothermal veins, easy to recognise thanks
to its often well formed, cubic crystals.
Arsenopyrite. By Jan Helebrant via Flickr.com
Arsenopyrite is an iron and arsenic sulphide
most common arsenic mineral. It can be granular or massive, or form
monoclinic crystals. It is silvery white when fresh but tarnishes to
pinkish and brownish colours. It is often found in hydrothermal veins
associated with quartz, gold and other hydrothermal minerals.
Cinnabar. By Orbital Joe via Flickr.com
Cinnabar is a
and a major mercury ore. It is most often granular or massive, but does
form crystals occasionally. It is scarlet or brownish red in colour. It
is a widely distributed mineral, often found near hot springs and
activity, associated to marcasite, pyrite, realgar, stibnite, quartz
Molybdenite. By Mike Beauregard via Flickr.com
molybdenite is a molybdenum
sulphide and the
most important molybdenum ore. It is a greasy, grey-coloured mineral
that can be scaly, massive, grainy, foliated or form hexagonal
crystals. It is found in hydrothermal veins, granitic rocks, or contact