By John Betterton

Sulfur, S, occurs at about 260 ppm in the Earth’s crust and its various minerals are very diverse and some are abundant.
World production currently stands at exceeds 70,000,000 tonnes per year. Most of it is recovered from fossil fuels from leading nations such as the USA, Canada, Russia, China, Saudi Arabia etc.
The industrial uses for sulfur are vast and range from vulcanisation of rubber, sulphuric acid, sulfur trioxide, numerous other chemical and pharmaceutical compounds, fertilizers, rust removal, explosives, fuels, paints, bleach papers, detergents, many organic compounds etc.


Sulfur is to be found in many examples from the sulfides, sulfosalts and sulfates groups. It is also present in other groups as well.

Sulfur, S, is an orthorhombic mineral that forms dipyramidal, tabular and disphenoidal crystals over 20 cm in size. Massive, reniform and powder habits are frequent.
It is typically sulfur-yellow in colour with honey-yellow, brownish, greenish, reddish and yellow grey tints. The lustre is resinous to greasy with a white streak. The mineral is transparent to translucent. It possesses several imperfect cleavages and a parting, and is somewhat sectile. The hardness is low at 1.5-2.5.Its specific gravity is 2.0 and has a low melting point.
The above physical properties are usually enough to identify it This species is commonly found as a sublimation product at volcanic fumaroles, resultant product of biological micro-organisms, low oxidation and acidic reactions in various mineral deposits and in many sedimentary rocks. It is associated with gypsum, anhydrite, halite, aragonite, calcite, celestine and
various sulphides etc. A great many countries produce sulfur specimens and includes the USA, Italy, Spain and Mexico.
Very occasionally sulfur has been cut into stones, but is too heat sensitive and soft for wider use.

Hauerite, MnS2, is reddish brown to brownish black mineral with a metallic - adamantine lustre.
It is opaque to translucent with a brownish red streak. It occurs as octahedral and as cubo-octahdral crystals. Globular
aggregates are also found. It has a perfect cleavage and an uneven to subconchoidal fracture, and is brittle.
The hardness is 4 and the specific gravity is 3.4. The cited properties, chemistry and occurrence help towards identification.
Hauerite is a low-temperature mineral regularly found with solfataric waters, in clay deposits rich in sulfur and from decomposed extrusive rocks. This mineral is accompanied by sulfur, realgar, gypsum and calcite. Locations for this species are to be found in the USA, Italy, Poland, Germany, Russia, China and New Zealand.

Cubanite, CuFe2S3, is a hydrothermal mineral formed at relatively high temperatures and as intimate orientated intergrowths, and as exsolved product. It is also present as an uncommon mineral in carbonaceous chondrites.
Chalcopyrite, pyrite, pyrrhotite, tetrahedrite, sphalerite, dolomite, calcite occur with it.
This species crystallises in the orthorhombic system with elongated, thick tabular crystals that are striated. Twinned crystals
are also common. Massive aggregates are also known. A parting exists with a conchoidal fracture.
It is strongly magnetic in character with a hardness of 3.5. The colour is brass to yellow with a metallic lustre. Its specific
gravity is 4.0.
The above properties, mode of occurrence aid in its identity. A great number of locations are known for cubanite and a few can be mentioned: In the USA, Canada, Sweden, Finland, Italy, Spain, Austria, France, Germany, Brazil, Argentina, Peru, Australia, Russia, Kazakhstan, China, Japan, and in numerous other countries.
Argentopyrite, AgFe2S3, occurs as orthorhombic, pseudohexagonal, thick tabular prisms with rough pyramidal terminations. Twinned crystals also are known.

It possesses an uneven fracture and is brittle. The hardness is 3.5 to 4 and the specific gravity is 4.2.
It is bright grey-white when fresh, frequently tarnished and iridescent in greens, blues, yellows, purples and browns.
The lustre is metallic.
Physical and chemical properties help in distinguishing this mineral.
Argentopyrite is found in hydrothermal veins associated with many interesting minerals like arsenic, proustite, pyrargyrite,
pyrostilpnite, xanthoconite, sternbergite, stephanite, pyrite, dolomite, quartz and calcite.
Notable sources for specimens are found in Germany, Czech Republic, France, Switzerland, Greece, Australia and the USA.

Cylindrite, Pb3Sn4FeSb2S14, is one of the more unusual minerals that occurs in the form of concentric spherical or tubular shells with good spiral development parallel to the elongation of the cylinders, and as aggregates.
Massive forms also occur and the mineral crystallises in the triclinic system. It has an excellent cleavage and is slightly malleable.
The mineral is blackish lead-grey in colour with a black streak. It is opaque with a metallic lustre. Its hardness is low at 2.5
with a specific gravity of 5.4. The cylindrical habit, occurrence type, the Sn-bearing associates are all that is needed here.
Cylindrite occurs in tin-bearing hydrothermal deposits with franckeite, stannite, incaite, potosiite, teallite, jamesonite, boulangerite, cassiterite, galena, pyrite and sphalerite. Bolivia is the famous country for samples. Also recorded from sites in Argentina, Russia and Ukraine.

Anhydrite, CaSO4, crystallises in the orthorhombic system with tabular or equant crystals with pinacoids, also elongated faces.
About 40 different forms have been documented.
Twinned crystals are present with rarer contact twins. Granular, nodular, fibrous and massive forms exist. The mineral is transparent to translucent with a white to pale grey streak.
Colour is variable from colourless, white, light blue, pale pink, mauve, light brown or grey. The lustre is pearly, vitreous to greasy.
Perfect, good to imperfect cleavages exist and the fracture is uneven to splintery in character.
Its hardness is 3-3.5 and it is brittle. The specific gravity is 2.9. The above characteristics and geological environment are useful clues.
Anydrite is a major mineral of sedimentary evaporate deposits and in cap rocks above salt domes, frequently created from the
dehydration of gypsum.

Also in various igneous rocks, fumarolic deposits, in hydrothermal deposits due alteration of other species.
It is accompanied by gypsum, halite, sylvite, polyhalite, dolomite, calcite, magnesite, celestine and sulfur etc.
There are hundreds of locations around the world for this mineral. Some are found in Austria, Germany, Switzerland, Italy, Czech Republic, USA, Canada, India, Japan and Madagascar.
Some cut gemstones have been made for gem collectors and are small, and less than 4 carats.

Susannite , Pb4(SO)4(CO)2(OH)2,
is a rare secondary mineral in the oxidation zone of hydrothermal Pb-bearing deposits.
It is found with such species as leadhillite, macphersonite , lanarkite, caledonite, cerussite and other minerals. It is a
hexagonal with equant to acute rhombohedral crystals modified by a prism and basal pinacoid.
The mineral is transparent to translucent with an adamantine lustre. It is colourless, white, pale green, pale yellow or brown.

The specific gravity is calculated at 6.5. X-rays are best for certain characterisation since it is trimorphous with leadhillite and
macphersonite. Many different sites are known for this attractive species and include those in: Scotland, Wales, Austria, France, Germany and Italy, it is also present at various slag locations for example Greece. Republic, France, Germany, Italy, Mexico, South Africa, England and the USA. Other minor occurrences also exist.


Corkite, PbFe3(PO)4(SO)4(OH)6,

crystallises in the trigonal system with pseudocubic, rhombohedral crystals. Crusts and massive habits are more common. It is transparent and is pale yellow, pale brown, yellowish green to dark green with a vitreous to resinous lustre. The mineral
possesses a perfect cleavage with a hardness of 3.5 to 4.5. Its specific gravity is 4.2.
Chemistry and x-rays are best for certain characterisation. Corkite is an uncommon secondary mineral formed at low temperatures or by the weathering in oxidised hydrothermal based-metal deposits.
It occurs with goethite, pyromophite, malachite, plumbojarosite, quartz, and parnauite.
This species has been found at various locations in Australia, Austria, Bulgaria, Czech Republic, France, Germany, Italy, Mexico, South Africa, England and the USA. Other minor occurrences also exist.

Hidalgoite, PbAl3(AsO)4(SO)4(OH)6,

is a colourless, white, pale green, dark green, pale yellow with a dull to vitreous lustre. The steak is white and is brittle.
It usually occurs as compact porcelaneous to porous masses. Rarely as small rhombohedral crystals forming intergrown
crystal groups. The hardness is 4.5 with an irregular to conchoidal fracture. Specific gravity is 3.7.
Chemistry and x-ray methods are best for positive characterisation. Hidalgoite is a rare secondary species of oxide zones
in polymetallic sulfide deposits with beudantite, mimetite, quartz, goethite, bayldonite, arsenopyrite, cerussite, and other species.
Countries that have supplied specimens include some of the following: Mexico, USA, England, Germany, Italy, Spain, Greece, Portugal, Australia and Namibia.

Hauyne, ( N a , C a ) 4 - 8Al6Si6(O,S)24(SO4,Cl)1-2,
crystallises in the cubic system with dodecahedral or pseudo-octahedral crystals to over 3 cm in size. Twinning is common but penetration twins are rare. It has a distinctive cleavage with an uneven to conchoidal fracture. The mineral is brittle with a hardness of 5.5-6, and a specific gravity of 2.4.
Hauyne may display a reddish orange to purplish pink fluorescence under LW UV light. This mineral is transparent to  translucent and can be bright blue, greenish blue, white, black, grey, brown, yellow and red in colour.
The streak is slightly bluish to colourless with a vitreous to greasy lustre. Crystal habit, mode of occurrence, physical properties all help towards its identification. It is found as an accessory mineral in phonolites and similar extrusive rocks,
hauynites and in volcanic rocks. Nepheline, leucite, andradite, melilite, augite, sanidine, biotite series, apatite group all accompany it.
Italy, Germany, France, Spain, Canada, USA, Afghanistan, Russia and Tajikistan have supplies examples of this attractive
species. Faceted gems averaging 22 carats in weight have been cut but are unusual. This mineral occurs in the rock type known
as lapis lazuli, an ancient gem.


 

To see a list of mineral, crystal, gemstone, fossil shows/events both UK and worldwide visit our show page, if you organise or know of a show please get in touch to list it here.

Copyright © 2020 Rock n Gem Magazine. All Rights Reserved.
Hosting and website design by EarthlygemsIT