Mineral "Sulfur & Calcite"
Machów mine, Tarnobrzeg City County, Subcarpathian Voivodeship, Poland, private collection from Netherlands.
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula S8. Elemental sulfur is a bright yellow, crystalline solid at room temperature. Sulfur is the tenth most abundant element by mass in the universe and the fifth most on Earth. Though sometimes found in pure, native form, sulfur on Earth usually occurs as sulfide and sulfate minerals. Being abundant in native form, sulfur was known in ancient times, being mentioned for its uses in ancient India, ancient Greece, China, and ancient Egypt. Historically and in literature sulfur is also called brimstone, which means "burning stone".
Crystals are usually yellow to yellowish-brown blocky dipyramids, with thick tabular and disphenoidal crystals less common. Also found more typically as powdery yellow coatings. Most native sulphur is found in sedimentary rocks, where large deposits are formed by reduction of sulfates, often biogenically. Sulfur is a common deposition product from volcanic gases associated with realgar, cinnabar and other minerals. It is also found in some vein deposits and as an alteration product of sulphide minerals.
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on scratch hardness comparison. Large calcite crystals are used in optical equipment, and limestone composed mostly of calcite has numerous uses.
Absolutely stunning, lustrous sulfur crystals formed over a bed of calcite with unknown mineral base. The condition of the sample is excellent. Age-related wear, fractures and minor cracks may appear. Dirt and dust. Size approx. 10,0cm x 8,0cm x 5,7cm. Weight c. 366g.