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.
Zinnwaldite, KLiFeAl(AlSi3)O10(OH,F)2, potassium lithium iron aluminium silicate hydroxide fluoride is a silicate mineral in the mica group. The IMA status is as a series between siderophyllite (KFe2Al(Al2Si2)O10(F,OH)2) and polylithionite (KLi2AlSi4O10(F,OH)2) and not considered a valid mineral species.
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.
Crookesite is a selenide mineral composed of copper and selenium with variable thallium and silver.
Hisingerite is an iron(III) phyllosilicate mineral with formula FeIII2Si2O5(OH)4 · 2 H2O. A black or dark brown, lustrous secondary mineral, it is formed by the weathering or hydrothermal alteration of other iron silicate and sulfide minerals.
Calderite is a mineral in the garnet group with the chemical formula (Mn2+, Ca)3(Fe3+, Al)2(SiO4)3.
Chloritoid is a silicate mineral of metamorphic origin. It is an iron magnesium manganese alumino-silicate hydroxide with formula (Fe, Mg, Mn)
2Al
4Si
2O
10(OH)
4. It occurs as greenish grey to black platy micaceous crystals and foliated masses. Its Mohs hardness is 6.5, unusually high for a platy mineral, and it has a specific gravity of 3.52 to 3.57. It typically occurs in phyllites, schists and marbles.
Geigerite is a mineral, a complex hydrous manganese arsenate with formula: Mn5(AsO3OH)2(AsO4)2·10H2O. It forms triclinic pinacoidal, vitreous, colorless to red to brown crystals. It has a Mohs hardness of 3 and a specific gravity of 3.05.
Jacobsite is a manganese iron oxide mineral. It is in the spinel group and forms a solid solution series with magnetite. The chemical formula is (Mn,Mg)Fe2O4 or with oxidation states and substitutions: (Mn2+,Fe2+,Mg)(Fe3+,Mn3+)2O4.
Zincobotryogen is a hydrous sulfate mineral with the chemical formula (Zn,Mg,Mn)Fe3+(SO4)2(OH)·7H2O. It forms bright orange red monoclinic prismatic crystals that exhibit a vitreous to greasy luster. Its specific gravity is 2.201 and it has a Mohs hardness of 2.5.
Arsenolite is an arsenic mineral, chemical formula As4O6. It is formed as an oxidation product of arsenic sulfides. Commonly found as small octahedra it is white, but impurities of realgar or orpiment may give it a pink or yellow hue. It can be associated with its dimorph claudetite (a monoclinic form of As2O3) as well as realgar (As4S4), orpiment (As2S3) and erythrite, Co3(AsO4)2·8H2O.
Sabatierite (Cu6TlSe4) is a mineral found in the Czech Republic. It is named for the French mineralogist Germain Sabatier (born 1923).
Ahlfeldite is a mineral of secondary origin. It is named after Friedrich Ahlfeld (1892–1982), a German-Bolivian mining engineer and geologist. Its type locality is Virgen de Surumi mine, Pakajake Canyon, Chayanta Province, Potosí Department, Bolivia.
Santite (KB5O8·4H2O) is a hydrated borate mineral of potassium found in Tuscany, Italy. It is named for Georgi Santi (1746–1823), a former director of the Museum of Natural History, Italy.
Piemontite is a sorosilicate mineral in the monoclinic crystal system with the chemical formula Ca2(Al,Mn3+,Fe3+)3(SiO4)(Si2O7)O(OH). It is a member of the epidote group.
Bukovite is a rare selenide mineral with formula Tl2Cu3FeSe4. It is a brown to black metallic mineral which crystallizes in the tetragonal system.
Marthozite is an orthorhombic mineral that has a general formula of Cu(UO2)3(SeO3)3(OH)2·7H2O. It was named after Belgian mineralogist Aimé Marthoz (1894-1962), former Director-general of the Union Minière du Haut Katanga - UMHK.
Demesmaekerite is a rare uranium selenite mineral with the chemical formula: Pb2Cu5(UO2)2(SeO3)6(OH)6·2H2O.
Guilleminite (Ba(UO2)3(SeO3)2(OH)4•3H2O) is a uranium mineral named by R. Pierrot, J. Toussaint, and T. Verbeek in 1965 in honor of Jean Claude Guillemin (1923–1994), a chemist and mineralogist. It is a rare uranium/selenium mineral found at the Musonoi Mine in the Katanga Province of the Democratic Republic of the Congo.
Derriksite is a very rare uranium mineral with the chemical formula Cu4(UO2)(SeO3)2(OH)6•H2O. It is a secondary mineral that contains copper, uranium and the rarer selenium. It is a bright green to duller bottle green colour. Its crystal habit is acicular, it is most likely to be found along with the uranyl selenium mineral demesmaekerite, but derriksite is much rarer than demesmaekerite. It is named after Jean Marie Francois Joseph Derriks (1912–1992), geologist and administrator of the Union Minière du Haut Katanga (UMHK). It has a Mohs hardness of about 2.
