Mimetite
Encyclopedia
Mimetite, whose name derives from the Greek Μιμητής mimethes, meaning "imitator", is an arsenate
mineral which forms as a secondary mineral in lead deposits, usually by the oxidation of galena
and arsenopyrite
. The name is a reference to mimetite's resemblance to the mineral pyromorphite
. This resemblance is not coincidental, as mimetite forms a mineral series with pyromorphite (Pb
5(4)3) and with vanadinite
(Pb
5(4)3). The most notable occurrences are Mapimi, Durango, Mexico and Tsumeb, Namibia.
Industrially, mimetite is a minor ore of lead
, especially when found in relatively large quantities. The chief use of mimetite is as a collector's specimen, often creating very attractive botryoidal crusts on the surface of the specimen. Though mimetite is also found in prismatic crystal forms, it is not used as a gemstone due to its softness. The best of these prismatic forms have been found in Johanngeorgenstadt in Saxony
and Wheal Unity in Cornwall
, England.
is the name for a variety with barrel shaped crystals of a brownish-red or orange-yellow color and containing a considerable proportion of phosphoric acid.
Arsenate
The arsenate ion is AsO43−.An arsenate is any compound that contains this ion. Arsenates are salts or esters of arsenic acid.The arsenic atom in arsenate has a valency of 5 and is also known as pentavalent arsenic or As[V]....
mineral which forms as a secondary mineral in lead deposits, usually by the oxidation of galena
Galena
Galena is the natural mineral form of lead sulfide. It is the most important lead ore mineral.Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the cubic crystal system often showing octahedral forms...
and arsenopyrite
Arsenopyrite
Arsenopyrite is an iron arsenic sulfide . It is a hard metallic, opaque, steel grey to silver white mineral with a relatively high specific gravity of 6.1. When dissolved in nitric acid, it releases elemental sulfur. When arsenopyrite is heated, it becomes magnetic and gives off toxic fumes...
. The name is a reference to mimetite's resemblance to the mineral pyromorphite
Pyromorphite
Pyromorphite is a mineral species composed of lead chlorophosphate: Pb53Cl, 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...
. This resemblance is not coincidental, as mimetite forms a mineral series with pyromorphite (Pb
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
5(4)3) and with vanadinite
Vanadinite
Vanadinite is a mineral belonging to the apatite group of phosphates, with the chemical formula Pb53Cl. It is one of the main industrial ores of the metal vanadium and a minor source of lead. A dense, brittle mineral, it is usually found in the form of red hexagonal crystals. It is an uncommon...
(Pb
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
5(4)3). The most notable occurrences are Mapimi, Durango, Mexico and Tsumeb, Namibia.
Uses of mimetite
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
, especially when found in relatively large quantities. The chief use of mimetite is as a collector's specimen, often creating very attractive botryoidal crusts on the surface of the specimen. Though mimetite is also found in prismatic crystal forms, it is not used as a gemstone due to its softness. The best of these prismatic forms have been found in Johanngeorgenstadt in Saxony
Saxony
The Free State of Saxony is a landlocked state of Germany, contingent with Brandenburg, Saxony Anhalt, Thuringia, Bavaria, the Czech Republic and Poland. It is the tenth-largest German state in area, with of Germany's sixteen states....
and Wheal Unity in Cornwall
Cornwall
Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...
, England.
Associated minerals
Mimetite is found in association with lead and arsenic minerals, including those minerals with which it forms a series. Some associated minerals include:- BelliteBelliteBellite is a mixture of minerals from Tasmania which forms attractive orange red crystals. Its empirical formula, PbCrO4,AsO4,SiO2 suggests a rather complex mixture of chromates and silicates of lead and arsenic. It is considered to be possibly, a mixture of crocoite, mimetite and quartz....
- CalciteCalciteCalcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
, - GalenaGalenaGalena is the natural mineral form of lead sulfide. It is the most important lead ore mineral.Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the cubic crystal system often showing octahedral forms...
, PbLeadLead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed... - PyromorphitePyromorphitePyromorphite is a mineral species composed of lead chlorophosphate: Pb53Cl, 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...
, PbLeadLead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
5(4)3 - SmithsoniteSmithsoniteSmithsonite, or zinc spar, is zinc carbonate , a mineral ore of zinc. Historically, smithsonite was identified with hemimorphite before it was realised that they were two distinct minerals. The two minerals are very similar in appearance and the term calamine has been used for both, leading to some...
, - VanadiniteVanadiniteVanadinite is a mineral belonging to the apatite group of phosphates, with the chemical formula Pb53Cl. It is one of the main industrial ores of the metal vanadium and a minor source of lead. A dense, brittle mineral, it is usually found in the form of red hexagonal crystals. It is an uncommon...
, PbLeadLead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
5(4)3 - WulfeniteWulfeniteWulfenite 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".It crystallizes...
, PbLeadLead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
4
Alternative names
Alternative names of mimetite include arsenopyromorphite, mimetesite, and prixite. CampyliteCampylite
Campylite is a variety of the lead arsenate mineral mimetite which received the name from the Greek 'kampylos'- bent, on account of the barrel-shaped bend of its crystals. It has also been used as an alternate name for pyromorphite....
is the name for a variety with barrel shaped crystals of a brownish-red or orange-yellow color and containing a considerable proportion of phosphoric acid.