PARATACAMITE
PARATACAMITE Paratacamite – Cu3(Cu,Zn)(OH)6Cl2 – is a rather rare halide and one of at least 15 common secondary copper minerals. It is a component of oxidized copper ores. It is classified within the Atacamite Group. It may contain Zn, but it is not a polymorph of atacamite. Varieties include paratacamite-(Mg) and paratacamite-(Ni). It is related […]
PHOSPHOSIDERITE
PHOSPHOSIDERITE Phosphosiderite – FePO4.2H2O – is a rather rare phosphate, typically found in very specific paragenetic associations. Recently, a massive pink variety of phosphosiderite has become available on the ornamental stone market in Brazil, where it is used for decorative items and ornaments. Phosphosiderite belongs to the Metavariscite Group; it is dimorphous with strengite and […]
POLYBASITE
POLYBASITE Polybasite – [(Ag,Cu)6(Sb,As)2S7][Ag9CuS4] – is a relatively common sulfosalt. It serves as a silver ore, as it contains 65.1% Ag and occurs in association with other silver minerals. It belongs to the Pearceite-Polybasite Group, forming a series with pearceite – [Ag9CuS4][(Ag,Cu)6(As,Sb)2S7] – with which it is isostructural. It is one of the four “ruby […]
PSEUDOMALACHITE
PSEUDOMALACHITE Pseudomalachite – Cu5(PO4)2(OH)4 – is a rare phosphate typical of the oxidized zones of copper deposits. It is a component of oxidized copper ores but is never the primary ore mineral of the deposit. It forms a Series with cornwallite and is isostructural with it. It is a polymorph of ludjibaite and reichenbachite – […]
PIGEONITE
PIGEONITE Pigeonite – (Mg,Fe2+,Ca)(Mg, Fe2+)[Si2O6] – is a relatively rare inosilicate that is difficult to identify. It is not an ore mineral. It is classified within the Pyroxene Supergroup, specifically the Clinopyroxene Subgroup. It may contain Na, Mn, K, H₂O, Ti, and Al. An Fe-rich variety exists. The terms “intermediate pigeonite” (at least 35% Mg […]
PLANCHEITE
PLANCHEITE Plancheite – Cu8(Si8O22)(OH)4.H2O – is an inosilicate belonging to the Amphibole Group. It is a very rare secondary copper mineral and does not constitute an ore. Macroscopically, it closely resembles shattuckite – which is also a blue inosilicate but belongs to the Pyroxene Group. It also resembles aurichalcite. Dense aggregates exhibit a structure similar […]
PARARAMMELSBERGITE
PARARAMMELSBERGITE Pararammelsbergite – NiAs2 – is an extremely rare arsenide found in Co-Ni-Ag-Bi-As ores. It is a member of the Löllingite Group and one of three NiAs2 polymorphs, alongside krutovite and rammelsbergite. It is the low-temperature polymorph. It may contain Co, Cu, and S. 1. Characteristics Crystal system: Orthorhombic pipyramidal. Color: […]
PHILLIPSITE
PHILLIPSITE Phillipsite – K(Ca,Na)[AlSiO]·12H2O – is a rarer tectosilicate from the Zeolite Group, Phillipsite Subgroup. It has no economic importance beyond being a collector’s mineral. “Phillipsite” is not actually a mineral, but a generic term referring to a group of minerals formed by Ca-phillipsite, K-phillipsite, and Na-phillipsite, which form series with each other. Of the […]
PRISMATINE
PRISMATINE Prismatine – (◻,Fe,Mg)(Mg,Al,Fe)5Al4Si2(Si,Al)2(B,Si,Al)(O,OH,F)22 – is an extremely rare sorosilicate, found in only a few locations on the planet. It has no economic importance. For many years, prismatine crystals were confused with kornerupine, with which it forms a solid solution. There is recent literature on the subject, which should be consulted for details. 1. Characteristics […]
POWELLITE
POWELLITE Powellite – Ca(MoO4) – is a rare molybdate that forms as a secondary mineral. It rarely forms an ore, despite molybdenum being a strategic element. Powellite crystals, on the other hand, fetch high prices in the collector mineral market. Powellite is classified in the Scheelite Group and forms a solid solution series (it is […]