Kyanite is a typically blue aluminosilicate mineral, found in aluminium-rich metamorphic pegmatites and sedimentary rock. It is the high pressure polymorph of andalusite and sillimanite, and the presence of kyanite in metamorphic rocks generally indicates metamorphism deep in the Earth's crust. Kyanite is also known as disthene or cyanite.
Prehnite is an inosilicate of calcium and aluminium with the formula: Ca2Al(AlSi3O10)(OH)2 with limited Fe3+ substitutes for aluminium in the structure. Prehnite crystallizes in the orthorhombic crystal system, and most often forms as stalactitic, botryoidal, reniform or globular aggregates, with only just the crests of small crystals showing any faces, which are almost always curved or composite. Very rarely will it form distinct, well-individualized crystals showing a square-like cross-section, including those found at the Jeffrey Mine in Asbestos, Quebec, Canada. Prehnite is brittle with an uneven fracture and a vitreous to pearly luster. Its hardness is 6.5, its specific gravity is 2.80–2.95 and its color varies from light green to yellow, but also colorless, blue, pink or white. In April 2000, rare orange prehnite was discovered in the Kalahari Manganese Fields, South Africa. Prehnite is mostly translucent, and rarely transparent.
Hornblende is a complex inosilicate series of minerals. It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole. Hornblende minerals are common in igneous and metamorphic rocks.
Axinite is a brown to violet-brown, or reddish-brown bladed group of minerals composed of calcium aluminium boro-silicate, (Ca,Fe,Mn)3Al2BO3Si4O12OH. Axinite is pyroelectric and piezoelectric.
Hemimorphite is the chemical compound Zn4(Si2O7)(OH)2·H2O, a component of mineral calamine. It is a silicate mineral which, together with smithsonite (ZnCO3), has been historically mined from the upper parts of zinc and lead ores. Both compounds were originally believed to be the same mineral and classified as calamine. In the second half of the 18th century, it was discovered that these two different compounds were both present in calamine. They closely resemble one another.
Cerussite (also known as lead carbonate or white lead ore) is a mineral consisting of lead carbonate (PbCO3), and is an important ore of lead. The name is from the Latin cerussa, white lead. Cerussa nativa was mentioned by Conrad Gessner in 1565, and in 1832 F. S. Beudant applied the name céruse to the mineral, whilst the present form, cerussite, is due to W. Haidinger (1845). Miners' names in early use were lead-spar and white-lead-ore.
Wulfenite is a lead molybdate mineral with the formula PbMoO4. It can be most often found as thin tabular crystals with a bright orange-red to yellow-orange color, sometimes brown, although the color can be highly variable. In its yellow form it is sometimes called "yellow lead ore".
Vivianite (Fe2+
3(PO
4)
2·8H
2O) is a hydrated iron phosphate mineral found in a number of geological environments. Small amounts of manganese Mn2+, magnesium Mg2+, and calcium Ca2+ may substitute for iron Fe2+ in the structure. Pure vivianite is colorless, but the mineral oxidizes very easily, changing the color, and it is usually found as deep blue to deep bluish green prismatic to flattened crystals.
Vivianite crystals are often found inside fossil shells, such as those of bivalves and gastropods, or attached to fossil bone.
Pyromorphite is a mineral species composed of lead chlorophosphate: Pb5(PO4)3Cl, sometimes occurring in sufficient abundance to be mined as an ore of lead. Crystals are common, and have the form of a hexagonal prism terminated by the basal planes, sometimes combined with narrow faces of a hexagonal pyramid. Crystals with a barrel-like curvature are not uncommon. Globular and reniform masses are also found. It is part of a series with two other minerals: mimetite (Pb5(AsO4)3Cl) and vanadinite (Pb5(VO4)3Cl), the resemblance in external characters is so close that, as a rule, it is only possible to distinguish between them by chemical tests. They were formerly confused under the names green lead ore and brown lead ore (German: Grünbleierz and Braunbleierz).
Mimetite is a lead arsenate chloride mineral (Pb5(AsO4)3Cl) which forms as a secondary mineral in lead deposits, usually by the oxidation of galena and arsenopyrite. The name derives from the Greek Μιμητής mimetes, meaning "imitator" and refers to mimetite's resemblance to the mineral pyromorphite. This resemblance is not coincidental, as mimetite forms a mineral series with pyromorphite (Pb5(PO4)3Cl) and with vanadinite (Pb5(VO4)3Cl). Notable occurrences are Mapimi, Durango, Mexico and Tsumeb, Namibia.
Caledonite, whose name derives from Caledonia, the historical name of its place of discovery (Scotland), is a richly colored blue-green sulfate-carbonate mineral of lead and copper with an orthorhombic crystal structure. It is an uncommon mineral found in the oxidized zones of copper-lead deposits.
Thomsonite is the name of a series of tecto-silicate minerals of the zeolite group. Prior to 1997, thomsonite was recognized as a mineral species, but a reclassification in 1997 by the International Mineralogical Association changed it to a series name, with the mineral species being named thomsonite-Ca and thomsonite-Sr. Thomsonite-Ca, by far the more common of the two, is a hydrous sodium, calcium and aluminium silicate, NaCa2Al5Si5O20·6H2O. Strontium can substitute for the calcium and the appropriate species name depends on the dominant element. The species are visually indistinguishable and the series name thomsonite is used whenever testing has not been performed. Globally, thomsonite is one of the rarer zeolites.
Howlite, a calcium borosilicate hydroxide (Ca2B5SiO9(OH)5), is a borate mineral found in evaporite deposits.
Cuprosklodowskite is a secondary uranium mineral formed by alteration of earlier uranium minerals. Its empirical formula is Cu(UO2)2(HSiO4)2·6(H2O). Cuprosklodowskite is a nesosilicate mineral, It is grass green to dark green in color, and its crystal habit is typically acicular, flat bladed crystals. It is a strongly radioactive mineral.
Mendipite is a rare mineral that was named in 1939 for the locality where it is found, the Mendip Hills in Somerset, England. It is an oxyhalide of lead with formula Pb3Cl2O2.
Semseyite is a rarely occurring sulfosalt mineral and is part of the class of lead antimony sulfides. It crystallizes in the monoclinic system with the chemical composition Pb9Sb8S21. The mineral forms dark gray to black aggregates.
Mereheadite is a rare oxychloride that can be found with Mendipite at Merehead quarry, Cranmore, Somerset, in the United Kingdom. Most specimens are associated with calcite, mendipite or hydrous cerussite in the Manganese pods on vein two at torr works quarry. This mineral is associated with symesite which is also light yellow to orange. Symesite is found in small blotches on the calcites or mendipites; Mereheadite does not, as it is most often found in veins.
Paralaurionite is a colorless mineral consisting of a basic lead chloride PbCl(OH) that is dimorphous with laurionite. It is a member of the matlockite group. The name is derived from para-, the Greek for "near", and laurionite, because of its polymorphic relationship to it. Bright, yellow tips of thorikosite can form on paralaurionite crystals and paralaurionite may also be intergrown with mendipite.
Diaboleite is a blue-colored mineral with formula Pb2CuCl2(OH)4. It was discovered in England in 1923 and named diaboleite, from the Greek word διά and boleite, meaning "distinct from boleite". The mineral has since been found in a number of countries.
Ianbruceite is a rare hydrated zinc arsenate with the formula [Zn2(OH)(H2O)(AsO4)](H2O)2; material from the Driggith mine has traces of cobalt. It was first discovered at Tsumeb, approved by the International Mineralogical Association as a new mineral species in 2011, reference IMA2011-49, and named for Ian Bruce, who founded "Crystal Classics" in the early 1990s, and was heavily involved in attempts to reopen the famous Tsumeb mine for specimen mining.
In 2013 new occurrences of ianbruceite were reported from the neighbouring Driggith and Potts Gill mines on High Pike in the Caldbeck Fells, Cumbria, England. Here the mineral is probably a post-mining product. Caldbeck Fells and Tsumeb are the only reported localities for ianbruceite to date (May 2013).
