Cadmium
Sulfide or Greenockite
CdS
Cadmium
sulfide (also sulphide), or the mineral greenockite, is an hexagonal,
yellowish crystal. It is a rare mineral on Earth and is the only real
ore of cadmium. It is a much sought after mineral because of its nice
color and crystal habit.
It has the same structure as that of zinc iron sulfide wurtzite. The
structure of Greenockite is composed of SCd4 tetrahedrons, which are
stacked in a layered structure with every other layer exactly the same
in an AB AB AB ... hexagonal sequence.
Crystals of greenockite are typically of six sided pyramids. In it
the hemimorphic character is easily seen because the top of the
crystal is the point and the bottom of it is its base.
Physical Properties of Cadmium Sulfide
| Color |
Honey yellow,
orange, red or light to dark brown. |
| Luster |
Adamantine to resinous. |
| Transparency |
Crystals are transparent to
translucent. |
| Crystal habits |
It includes small tapering
hemimorphic six added pyramids and platy hexagonal crystals. It is
also seen as crusts or dustings over crystals of calcite,
smithsonite and sphalerite. |
| Cleavage |
Poor in one direction (basal)
and good in three other directions (prismatic). |
| Fracture |
Conchoidal. |
| Hardness |
3 - 3.5 |
| Specific gravity |
Approximately 4.5 - 5 (much
heavier than average). |
| Streak |
Red, orange or light brown. |
|
