Hemihedrite

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Hemihedrite
Hemihedrite-phoenicochroite-537207.jpg
Red phoenicochroite and orange hemihedrite microcrystals richly cover the matrix
General
Category Chromate mineral
Formula
(repeating unit)
Pb10Zn(CrO4)6(SiO4)2(F,OH)2
IMA symbol Hhe [1]
Strunz classification 7.FC.15
Crystal system Triclinic
Space group P1 (No. 2)
Unit cell a = 9.49, b = 11.44
c = 10.84 [Å]; α = 120.5°
β = 92.1°, γ = 55.83°; Z = 1
Identification
ColorBright orange, henna-brown, to almost black
Crystal habit Euhedral crystals with hemihedral morphology
Twinning Present
Mohs scale hardness3
Luster Vitreous
Streak Saffron-yellow
Diaphaneity Translucent to transparent
Specific gravity 6.42
Optical propertiesBiaxial (+)
Refractive index nα = 2.105 nβ = 2.320 nγ = 2.650
Birefringence δ = 0.545
Pleochroism Feeble, yellow to orange
2V angle 88° (measured)
References [2] [3] [4] [5] [6]

Hemihedrite is a rare lead zinc chromate silicate mineral with formula Pb10Zn(CrO4)6(SiO4)2(F,OH)2. It forms a series with the copper analogue iranite. [3]

Discovery and occurrence

Hemihedrite was first described in 1967 for occurrences in the Florence lead silver mine in the Ripsey District, Tortilla Mountains, Pinal County, Arizona, US. [3] It was named for the hemihedral morphology of its crystals. [2]

It occurs in oxidized veins containing galena, sphalerite and pyrite. Associated secondary minerals include cerussite, phoenicochroite, vauquelinite, willemite, wulfenite, galena, sphalerite, pyrite, tennantite and chalcopyrite. [2] It has been reported from several mining districts in Arizona and one in Nevada. It has also been reported from the Antofagasta Region of Chile and the Anarak District of Esfahan Province, Iran. [3]


Related Research Articles

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Sphalerite is a sulfide mineral with the chemical formula (Zn,Fe)S. It is the most important ore of zinc. Sphalerite is found in a variety of deposit types, but it is primarily in sedimentary exhalative, Mississippi-Valley type, and volcanogenic massive sulfide deposits. It is found in association with galena, chalcopyrite, pyrite, calcite, dolomite, quartz, rhodochrosite, and fluorite.

<span class="mw-page-title-main">Greenockite</span>

Greenockite is a rare cadmium bearing metal sulfide mineral consisting of cadmium sulfide (CdS) in crystalline form. Greenockite crystallizes in the hexagonal system. It occurs as massive encrustations and as hemimorphic six-sided pyramidal crystals which vary in color from a honey yellow through shades of red to brown. The Mohs hardness is 3 to 3.5 and the specific gravity is 4.8 to 4.9.

<span class="mw-page-title-main">Germanite</span>

Germanite is a rare copper iron germanium sulfide mineral, Cu26Fe4Ge4S32. It was first discovered in 1922, and named for its germanium content. It is only a minor source of this important semiconductor element, which is mainly derived from the processing of the zinc sulfide mineral sphalerite. Germanite contains gallium, zinc, molybdenum, arsenic, and vanadium as impurities.

<span class="mw-page-title-main">Galena</span> Natural mineral form of lead sulfide

Galena, also called lead glance, is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver.

<span class="mw-page-title-main">Chalcocite</span> Sulfide mineral

Chalcocite, copper(I) sulfide (Cu2S), is an important copper ore mineral. It is opaque and dark gray to black, with a metallic luster. It has a hardness of 2.5–3 on the Mohs scale. It is a sulfide with a monoclinic crystal system.

<span class="mw-page-title-main">Marcasite</span> Iron disulfide (FeS2) with orthorhombic crystal structure

The mineral marcasite, sometimes called “white iron pyrite”, is iron sulfide (FeS2) with orthorhombic crystal structure. It is physically and crystallographically distinct from pyrite, which is iron sulfide with cubic crystal structure. Both structures do have in common that they contain the disulfide S22− ion, having a short bonding distance between the sulfur atoms. The structures differ in how these di-anions are arranged around the Fe2+ cations. Marcasite is lighter and more brittle than pyrite. Specimens of marcasite often crumble and break up due to the unstable crystal structure.

<span class="mw-page-title-main">Wurtzite</span>

Wurtzite is a zinc and iron sulfide mineral with the chemical formula (Zn,Fe)S, a less frequently encountered structural polymorph form of sphalerite. The iron content is variable up to eight percent. It is trimorphous with matraite and sphalerite.

<span class="mw-page-title-main">Mimetite</span> Lead arsenate chloride mineral

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.

<span class="mw-page-title-main">Alstonite</span>

Alstonite, also known as bromlite, is a low temperature hydrothermal mineral that is a rare double carbonate of calcium and barium with the formula BaCa(CO
3
)
2
, sometimes with some strontium. Barytocalcite and paralstonite have the same formula but different structures, so these three minerals are said to be trimorphous. Alstonite is triclinic but barytocalcite is monoclinic and paralstonite is trigonal. The species was named Bromlite by Thomas Thomson in 1837 after the Bromley-Hill mine, and alstonite by August Breithaupt of the Freiberg Mining Academy in 1841, after Alston, Cumbria, the base of operations of the mineral dealer from whom the first samples were obtained by Thomson in 1834. Both of these names have been in common use.

<span class="mw-page-title-main">Bournonite</span> Sulfosalt mineral species

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<span class="mw-page-title-main">Stephanite</span>

Stephanite is a silver antimony sulfosalt mineral with formula: Ag5SbS4. It is composed of 68.8% silver, and sometimes is of importance as an ore of this metal.

<span class="mw-page-title-main">Enargite</span> Sulfosalt mineral

Enargite is a copper arsenic sulfosalt mineral with formula Cu3AsS4. It takes its name from the Greek word enarge, "distinct". Enargite is a steel gray, blackish gray, to violet black mineral with metallic luster. It forms slender orthorhombic prisms as well as massive aggregates. It has a hardness of 3 and a specific gravity of 4.45.

<span class="mw-page-title-main">Nagyágite</span> Sulfide mineral

Nagyágite is a rare sulfide mineral with known occurrence associated with gold ores. Nagyágite crystals are opaque, monoclinic and dark grey to black coloured.

<span class="mw-page-title-main">Uchucchacuaite</span>

Uchucchacuaite (AgMnPb3Sb5S12) is a rare sulfosalt mineral found in hydrothermal deposits.

<span class="mw-page-title-main">Alabandite</span>

Alabandite or alabandine is a rarely occurring manganese sulfide mineral. It crystallizes in the cubic crystal system with the chemical composition Mn2+S and develops commonly massive to granular aggregates, but rarely also cubic or octahedral crystals to 1 cm.

Xilingolite is a lead sulfide mineral with formula Pb3Bi2S6. It has a hardness of 3, a metallic luster, and usually exhibits a lead-grey color. It is a dimorph of lillianite, exhibiting increased Pb-Bi order and decreased symmetry.

<span class="mw-page-title-main">Semseyite</span>

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.

Guettardite is a rare arsenic-antimony lead sulfosalt mineral with the chemical formula Pb(Sb,As)2S4. It forms gray black metallic prismatic to acicular crystals with monoclinic symmetry. It is a dimorph of the triclinic twinnite.

Teineite is a tellurite mineral with the formula Cu(TeO3). 2 H2O. It has a Mohs hardness of 2.5 and it comes in many different shades of blue, ranging from cerulean blue to bluish-gray. The mineral millsite has the same chemical composition, but crystallizes in the monoclinic system, while teineite crystallizes in the orthorhombic system.

<span class="mw-page-title-main">Segnitite</span> Common iron oxide mineral

Segnitite is a lead iron(III) arsenate mineral. Segnitite was first found in the Broken Hill ore deposit in Broken Hill, New South Wales, Australia. In 1991, segnitite was approved as a new mineral. Segnitite has since been found worldwide near similar locality types where rocks are rich in zinc and lead especially. it was named for Australian mineralogist, gemologist and petrologist Edgar Ralph Segnit. The mineral was named after E. R. Segnit due to his contributions to Australian mineralogy.

References

  1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID   235729616.
  2. 1 2 3 Handbook of Mineralogy
  3. 1 2 3 4 Hemihedrite on Mindat.org
  4. Hemihedrite data on Webmineral
  5. Mineralienatlas
  6. McLean, W.J.; Anthony, J.W. (1970). "The crystal structure of hemihedrite". American Mineralogist. 55: 1103–1114.