PLAGIOCLASE
PLAGIOCLASE Plagioclase – NaAlSi3O8 – CaAl2Si2O8 – is a very common rock-forming tectosilicate, the second most abundant mineral in the Earth’s crust, just behind quartz. It is an industrial mineral with many uses. “Plagioclase” is not actually a mineral, but a term used for the members of the solid solution between albite (Ab) (NaAlSi3O8) and […]
PHOSPHORITE
PHOSPHORITE Phosphorus is a strategic element, as it is essential for agriculture, integrated into NPK fertilizers. There is no substitute for P in agriculture. Phosphate is also widely used as an animal feed supplement and in the chemical industry. The only sources of P are the so-called “phosphate rocks,” which can be of two types: […]
PHENGITE
PHENGITE See “Muscovite”. Phengite is a variety of Muscovite.
PYRARGYRITE
PYRARGYRITE Pyrargyrite – Ag3SbS3 – is a very rare sulfosalt, an important ore of Ag. In the deposits, its volume varies a lot, only in some cases it is the main Ag ore. It’s called “ruby silver ore”. The mining term “ruby silvers” is used interchangeably for proustite, pyrargyrite, miargyrite and polybasite. Pyrargyrite is extremely […]
PHOSGENITE
PHOSGENITE Phosgenite – PbCO3Cl2 – is a fairly rare carbonate, typical of alteration (oxidation) zones of Pb sulfide deposits. Due to its rarity, it is not considered an ore. Phosgenite has some special characteristics: – the hardness in the mineral is anisotropic, as in kyanite; in this case the hardness in {110} is lower parallel […]
PYROMORPHITE
PYROMORPHITE Pyromorphite – Pb5(PO4)3Cl – is a relatively common phosphate, a secondary mineral that integrates polymetallic oxidized ores. It is never the main ore mineral. It is classified in the Apatite Group, a group of isomorphic hexagonal minerals. Forms an isomorphic series (is isostructural) with mimetite and vanadinite. In many cases, the minerals are so […]
PYRITE
PYRITE Pyrite – FeS2 – is the most common and abundant sulfide, occurring in igneous, metamorphic and sedimentary rocks, in addition to being present in many types of sulfidic and oxidized ores. Pyrite is normally very pure, but may contain Ni, Co, Cu, Zn, Au, Ag, Pb, V, Se and As. It is the cubic […]
PUMPELLYITE
PUMPELLYITE Pumpellyite – Ca2(Al,Fe2+,Fe3+,Mg,Mn)Al2[(OH)2|SiO4|Si2O7].H2O – is a relatively rare sorosilicate, indicative of a certain metamorphic grade. It has no economic importance. “Pumpellyite” is actually not a mineral, but just a generic, informal name referring to the minerals that make up the 11-member Pumpellyite Group. Of these, 5 are “pumpellyite”: pumpellyite-(Al), pumpellyite-(Fe+2), pumpellyite-(Fe+3), pumpellyite-(Mg) and pumpellyite-(Mn+2). […]
PECTOLITE
PECTOLITE Pectolite – NaCa2Si3O8(OH) – is a very rare inosilicate that occurs in some very specific paragenesis. The well-known massive blue “larimar” variety, found only in the Dominican Republic, is mined as gemological material. It is classified in the Wollastonite Group, in the Pectolite-Sérandite Series, constituting the Ca analogue of sérandite. May contain H2O, K, […]
PENTLANDITE
PENTLANDITE Pentlandite – (Fe,Ni)9S8 -is the most common Ni sulfide, an important Ni ore like garnierite.It is the most common mineral in the Pentlandite Group; the other members of the Group are rare. Pentlandite has a chemical composition very close to the ideal formula; usually a little more Ni than Fe and generally contains some […]