HOLLANDITE
HOLLANDITE Hollandite – Ba(Mn4+6,Mn3+2)O16 – is a relatively common oxide that is part of some Mn ores. In 2012, the IMA revised the nomenclature of the Hollandite Supergroup. Now hollandite is redefined as the Ba-Mn3+ end of the Coronadite Group. Classical hollandite was redefined as ferrihollandite, a name that designates the Ba-Fe3+ end of the […]
HOLMQUISTITE
HOLMQUISTITE Holmquistite – {Li2}{Mg3Al2}(Si8O22)(OH)2 – is a very rare amphibole that occurs associated with lithium-bearing pegmatites. It does not form ore, but it serves as a guide in the identification of lithium-bearing pegmatites (see London, D. 1986, Holmquistite as a Guide to Pegmatitic Rare Metal Deposits. Economic Geology, v. 81, p. 704-712). The Holmquistite Group […]
HOPEITE
HOPEITE Hopeite – Zn3(PO4)2·4H2O – is a rare phosphate that occurs in some very specific geological environments. It is part of Zn ores, but is never the main ore mineral in the deposit. It is classified in the Hopeite Group and is the phosphate analog of arsenohopeite. It has two varieties, α-hopeite and β-hopeite. It […]
HAKITE-(Hg)
HAKITE-(Hg) Hakite – (Cu,Hg)3(Sb,As)(Se,S)3 – is an extremely rare sulfosalt (selenide). It has no importance as an ore. It is classified in the Tetrahedrite Group, in the Hakite Subgroup, together with hakite-(Cd), hakite-(Fe) and hakite-(Zn). It contains 26.18% Cu, 16.53% Hg, 16.05% Sb, 3.70% As, 33.83% Se, and 3.70% S. 1. Characteristics Crystal system: Cubic […]
HEULANDITE
HEULANDITE Heulandite – (Ca,Na,K)5(Si27Al9)O72.26H2O – is a tectosilicate of the Zeolite Group. It is a very common mineral, abundant in certain situations. It has great importance as an ore when it occurs cryptocrystalline. When it occurs hydrothermal, in larger crystals, it has only some importance as a collection mineral. “Heulandite” is actually not a mineral, […]
HEDENBERGITE
HEDENBERGITE Hedenbergite – CaFe2+Si2O6 – is an inosilicate, a rarer monoclinic pyroxene (clinopyroxene), characteristic of very specific paragenesis. It has no economic importance. It is part of the diopside – augite – hedenbergite solid solution series and may contain, as impurities, Ti, Mg, Mn, Na, K, Al and Zn. It forms epitaxy with babingtonite and […]
HORNBLENDE BROWN
BROWN HORNBLENDE Brown hornblende – Na(2)Ca(2)(Mg,Fe2+)4(Fe3+,Ti,Al)(OH)2|AlSi7O22 – is an inosilicate of the Amphibole Supergroup. It is a rarer mineral, characteristic of some types of igneous rocks. It has no economic importance. “Brown Hornblende” is actually not a mineral, but just an informal name, a nickname, for brown to black amphiboles of complex compositions such as […]
HERCYNITE
HERCYNITE Hercynite – FeAl2O4 – is a relatively common oxide that occurs mainly as an accessory mineral in some types of igneous rocks. It has no economic importance. Hercynite is one of the members of the Spinel Group and forms three series: with spinel, with gahnite, and with chromite. Like all members of the Spinel […]
HAÜYNE
HAÜYNE Haüyne – (Na,Ca)4-8(Al6Si6(O,S)24)(SO4,Cl)1-2 – is a tectosilicate, a relatively rare feldspathoid, characteristic of silica-subsaturated sodic volcanic rocks. It is sought after as a collector mineral and can be used as a gemstone. Haüyne is part of the Sodalite Group, along with lazurite, nosean, sodalite, tsaregorodtsevite and vladimirivanovite. It may contain some K. There is […]
HAUSMANNITE
HAUSMANNITE Hausmannite – Mn3O4 – is a relatively rare oxide that can occur in a variety of geological situations. Generally hausmannite is an ore of Mn of secondary importance; only in some deposits it has economic importance. It forms crystals up to 7.5 cm. 1. Characteristics Crystal system: Tetragonal, bipiramidal ditetragonal. Color: Black-brown to grayish. […]