Drysdallite is a rare molybdenum

selenium Selenium is a chemical element with the symbol Se and atomic number 34. It is a nonmetal (more rarely considered a metalloid) with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, ...

sulfide mineral The sulfide minerals are a class of minerals containing sulfide (S2−) or disulfide (S22−) as the major anion. Some sulfide minerals are economically important as metal ores. The sulfide class also includes the selenides, the tellurides, th ...

with formula Mo(Se,S)₂. It crystallizes in the

hexagonal In geometry, a hexagon (from Greek , , meaning "six", and , , meaning "corner, angle") is a six-sided polygon. The total of the internal angles of any simple (non-self-intersecting) hexagon is 720°. Regular hexagon A '' regular hexagon'' has ...

system as small pyramidal crystals or in cleavable masses. It is an opaque metallic mineral with a

Mohs hardness The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by t ...

of 1 to 1.5 and a

specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water at its densest ...

of 6.25. Like

molybdenite Molybdenite is a mineral of molybdenum disulfide, Mo S2. Similar in appearance and feel to graphite, molybdenite has a lubricating effect that is a consequence of its layered structure. The atomic structure consists of a sheet of molybdenum ato ...

it is pliable with perfect cleavage. It was first described in 1973 for an occurrence in an oxidized uranium deposit near

Solwezi Solwezi is a town in Zambia. It is the provincial capital of the mineral-rich North-Western Province. Solwezi is also the administrative capital of Solwezi District, one of the eleven districts in the North-Western Province. Location Solwezi ...

Zambia Zambia (), officially the Republic of Zambia, is a landlocked country at the crossroads of Central, Southern and East Africa, although it is typically referred to as being in Southern Africa at its most central point. Its neighbours are t ...

. It was named for Alan Roy Drysdall, the director of the Zambian geological survey.

References

Handbook of Mineralogy

Webmineral

Molybdenum minerals Sulfide minerals Selenide minerals Hexagonal minerals Minerals in space group 194 {{sulfide-mineral-stub