Paradamite is a rare polymorph of the more common Adamite . It is chemically the same... More
Paradamite is a rare polymorph of the more common Adamite. It is chemically the same mineral type as Adamite, but being that it crystallizes in a different crystal system, it is scientifically recognized as an individual mineral type. It is generally very hard to distinguish from regular Adamite by looks alone. Paradamite crystals are almost always embedded in rusting, crumbly, brown Limonite that stains the hands. Hide
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Pararealgar is the alteration product of the mineral Realgar . It forms when Realgar ... More
Pararealgar is the alteration product of the mineral Realgar. It forms when Realgar is exposed to light, which causes a physical change in the structure of the mineral and transforms it into a new mineral. Pararealgar is has the same chemical composition and chemical formula as Realgar, but its crystal form differs. Pararealgar is also different in color than Realgar; whereas Realgar is bright red, Pararealgar is bright orange or yellow, and additionally has a more powdery consistency. Pararealgar is usually associated with Realgar, and specimens can be partially altered. It is not uncommon for specimens to be only partially altered in sections, creating yellow and red color zones. Once a significant alteration has taken place, the mineral will start to crumble. The
alteration mineral that Realgar transformed into was generally
assumed to be Orpiment, but recent scientific analysis has in fact
determined the orange alteration product as Pararealgar. Pararealgar, like Realgar, is photosensitive, and will become
unstable and eventually crumble into a yellow powder if left in the
light. Specimens should be stored enclosed and covered
to prevent their exposure to light.
Pararealgar contains a significant amount of poisonous arsenic, and is
itself somewhat toxic. Washing hands is recommended after handling specimens, especially if they are powdery. Hide
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Pargasite is a member of the extended Hornblende group. Most Hornblendes, including P... More
Pargasite is a member of the extended Hornblende group. Most Hornblendes, including Pargasite, are dark and opaque, however Pargasite can also be lightly colored and transparent. Some forms of Pargasite are especially known for their electric green color and gemmy appearance. There are several variations of this mineral with different elemental substitutions. Some of these are recognized as individual minerals, thereby making Pargasite a mineral group, with Pargasite as the dominating member. Pargasite is named after the locality of Pargas, Finland, where this mineral was first described. Hide
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Pearceite nbsp is an uncommon mineral containing silver and copper in its structure. ... More
Pearceite is an uncommon mineral containing silver and copper in its structure. It forms a series with Polybasite, with Pearceite being the arsenic-rich member and Polybasite being the antimony-rich member. It is often not possible to visually distinguish these two minerals from each other. Pearceite is named in honor of Dr. Richard Pearce (1837-1927), a Cornish-American chemist from Colorado. Hide
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Pectolite is a unique mineral known for its interesting crystal habits. Its crystals ... More
Pectolite is a unique mineral known for its interesting crystal habits. Its crystals primarily form as extremely slender and elongated densely grouped fragile fibers radiating from a central point outwards. When the fibers are very densely-packed, the result formation is as thick, globular masses. Pectolite can be tough and dense, but is often very delicate and soft to the touch. It can be dented by just touching it too hard, and thin splinters are easily broken when handled. Pectolite specimens are also known to give splinters when handling due to their slender and brittle crystals which easily break. Hide
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div Pentlandite is an important mineral due to its nickel content, but it rarely form... More
Pentlandite is an important mineral due to its nickel content, but it rarely forms in interesting specimens for collectors. It usually occurs together with Pyrrhotite, and may even be intergrown together with it.
Pentlandite is both an individual mineral, and the name of a mineral group. The Pentlandite group is composed of rare sulfides that have similar chemical structures, with Pentlandite being the most prominent member of the group. Pentlandite is named in honor of Joseph Barclay Pentland (1797–1873), a natural scientist from Ireland who first identified this mineral.
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Pezzottaite is a mineral that is very similar to Beryl , but it contains lithium as w... More
Pezzottaite is a mineral that is very similar to Beryl, but it contains lithium as well as the rare
element cesium replacing some beryllium in its chemical
structure. It is therefore scientifically classified as a separate mineral species from Beryl. When first found, it was though to be a variety of Beryl, but it wasn't until 2003 that the IMA regarded Pezzottaite as a unique mineral species. It is named after Italian geologist Dr. Federico Pezzotta of Milan. Hide
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div Phenakite is an attractive and rare mineral, forming in aesthetic crystals that a... More
Phenakite is an attractive and rare mineral, forming in aesthetic crystals that are highly desirable to collectors. It is named from the the Greek word phenakos - "deceiver", describing this mineral's visual similarity to Quartz.
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Phlogopite is a common form of mica , and it is usually distinguished by its brownish... More
Phlogopite is a common form of mica, and it is usually distinguished by its brownish-red color. Phlogopite, like the other important mica's, can come in
very large crystal sheets. Thin
sheets can be peeled off as layers, and thin layers maintain an interesting metallic-looking transparency. Biotite, another common mica, is recognized by the IMA as a mineral group of related micas rather then as an individual mineral type. Phlogopite is one of the member minerals of the Biotite group, and is chemically and structurally similar to the other Biotite minerals. It represents the magnesium rich end member of the Biotite group, whereas the other forms of Biotite are rich in iron. Phlogopite contains three closely related minerals (some consider these as varieties): - Tetraferriphlogopite: KMg 3(Fe 3+Si 3O 10)(OH) 2- Shirozulite: KMn 3(AlSi 3O 10)(OH,F) 2- Fluorophlogopite: KMg 3(AlSi 3O 10)F 2Phlogopite is very hard to clean because if washed
it will absorb water internally and start to break apart. The best way
to wash Phlogopite and other micas is with a dry electric toothbrush. Hide
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Phosgenite is very rare, and good crystals are highly cherished among experienced min... More
Phosgenite is very rare, and good crystals are highly cherished among experienced mineral collectors, commanding very high prices. The large crystals that were found in Monteponi in Italy are true legendary classics. Phosgenite is a difficult mineral to obtain, with no significant discoveries in recent times. Hide
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Below is an image for each one of the members of the Plagioclase group. Additional images of each member mineral is indexed on the individual member pages.
The Plagioclase series is a group of related feldspar minerals that essentially have ... More
The Plagioclase series is a group of related feldspar minerals that essentially have the same formula but vary in their percentage of sodium and calcium. Albite and Anorthite are the end members of the series, with the intermediary minerals Oligoclase, Andesine, Labradorite, and Bytownite. The acclaimed Dana's System of
Mineralogy lists the intermediary members as individual minerals,
whereas the IMA does not recognize them as individual mineral
species. Thus, some consider Oligoclase and Andesine to be a variety of
Albite, and Labradorite and Bytownite to be a variety of Anorthite. For convenience to the reader, this guide will dedicate a page for each intermediary member. The Plagioclase Feldspars are important rock-forming minerals and occur in numerous mineral environments. In many instances, it is very hard to tell apart one from another. When a particular Plagioclase Feldspar cannot be identified, it is simply called "Plagioclase" or "Plagioclase Feldspar". The percentages of sodium and calcium for each member listed above are an approximate value; the actual percentage can vary as much as 20 percent. Hide
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Platinum is the rarest and most expensive of the popular precious metals. It is much ... More
Platinum is the rarest and most expensive of the popular precious metals. It is much rarer then Gold. Due to its rarity and value, it is not readily available to mineral collectors and is seldom represented in in all but the highest-end mineral collections. Natural Platinum is fairly impure. It is always associated with small amounts of other elements such as iron, gold, copper, and nickel, and may also contain the rare metals iridium, osmium, rhodium, and palladium. These impurities can lower its specific gravity to as much as 14, whereas pure elemental platinum is 21.4. Most Platinum specimens contain traces of iron, which may cause it to be slightly attracted to magnetic fields. For additional information, see the gemstone section on Platinum. Hide
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div div Polybasite is an uncommon mineral containing silver and copper in its structu... More
Polybasite is an uncommon mineral containing silver and copper in its structure. It is almost always found in known silver deposits, often in association with Stephanite. Polybasite forms a series with Pearceite, with Polybasite being the antimony-rich member, and Pearceite being the arsenic-rich member. It is often not possible to visually distinguish these two minerals from each other. Polybasite is named from the Greek words, poly, "many" and basis, "base" referring to its composition of several metallic and submetallic elements.
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Powellite is very similar to the mineral Scheelite , though it is much rarer. It form... More
Powellite is very similar to the mineral Scheelite, though it is much rarer. It forms a series with that mineral, and contains tungsten in place of the molybdenum. Powellite often forms as an alteration product of Molybdenite, sometimes only partially replacings it. Powellite is named after geologist John Wesley Powell (1834–1902), a director for the United States Geological Survey. Hide
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Prehnite forms in both odd and distinct formation habits. It most often occurs as rou... More
Prehnite forms in both odd and distinct formation habits. It most often occurs as rounded or bubbly crystal masses, and commonly forms odd-shaped epimorphs after Anhydrite, Glauberite, and Laumontite. These epimorphs are remarkable for having hollow centers of a dissolved early-stage mineral. Elongated Prehnite formations are almost always rounded at the head and resemble fingers, and they are affectionately called "Prehnite Fingers" by collectors. A particularly desirable formation, known as a snakehead, describes an elongated Prehnite epimorph with a widened head. Prehnite sometimes has a brown ferrous coating, which can be removed with chemicals. Some dealers treat specimens by oiling them with lubricants to enhance luster. Prehnite is named after Colonel Hendrik Von Prehn (1733–1785), a Dutch commander of the military forces of South Africa who brought Prehnite specimens from South Africa to Europe. For additional information, see the gemstone section on Prehnite. Hide
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div Proustite is an interesting mineral that contains silver in its chemical structur... More
Proustite is an interesting mineral that contains silver in its chemical structure. It is one of the few silver-bearing minerals that can exhibit transparency. Proustite is usually transparent, with deep-red crystals, but may also be a darker, more metallic-looking form. However, even darker, more metallic Proustite will be visibly red and transparent when backlit.
Proustite is light sensitive. Prolonged exposure to bright light will darken its transparency and cause it to become darker. Exposure also may cause a dark, dull film to form on crystal faces; this film can be removed by brushing a specimen with soap and water.
Proustite is very similar to Pyrargyrite, and forms a series with it. Proustite is the arsenic-rich member, and Pyrargyrite is the antimony-rich member. It is often not possible to visually distinguish these two minerals from each other, though Proustite is usually lighter in color. Most good material in collections today are from closed, historical localities.
Proustite is named in honor of Joseph Louis Proust (1754-1826), a French chemist famous for defining the law of definite proportions, also known as Proust's Law.
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div Psilomelane describes barium manganese hydroxides that do not form in visible cry... More
Psilomelane describes barium manganese hydroxides that do not form in visible crystals. Originally recognized as an individual mineral species, Psilomelane was discredited by the IMA in 1982. However, the name is still in use today, describing manganese hydroxides such as Romanechite and Hollandite that are not specifically identified and sometimes even admixed together.
Psilomelane can be banded with Pyrolusite, with alternating layers of light and dark gray bands. It is named after the Green term " psilos", meaning smooth, and " melas", meaning black.
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div Pumpellyite is a group of closely related minerals that have a minor of variation... More
Pumpellyite is a group of closely related minerals that have a minor of variation of elements among members. Pumpellyite-(Mg) and Pumpellyite-(Fe 2+) are the most common members, with the other members being rare. In addition to members that have the name designation of Pumpellyite with an added chemical suffix, there are additional extended Pumpellyite group members not discussed in this guide that have their own unique names. Due to the difficulty in distinguishing Pumpellyite members, most specimens are labelled simply as Pumpellyite, without the chemical suffix. However, sometimes a locality is known to produce one type of member, and this can determine the specific form of Pumpellyite.
Pumpellyite was named in 1925 in honor of geologist Raphael Pumpelly (1837-1923), a professor of Mining Science at Harvard University. Pumpelly surveyed the copper region of Michigan, where this mineral was first described.
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div Pyrargyrite is an interesting mineral that contains silver in its chemical struct... More
Pyrargyrite is an interesting mineral that contains silver in its chemical structure. It is one of the few silver-bearing minerals that can exhibit transparency. Pyrargyrite contains two very distinct habits: as transparent, deep-red crystals, and in opaque, dark-metallic gray form. Many of the opaque and metallic-looking specimens will still exhibit slight transparency and red color when backlit.
Pyrargyrite is light sensitive. Prolonged exposure to bright light will darken its transparency and cause it to become darker. Exposure also may cause a dark, dull film to form on crystal faces; this film can be removed by brushing a specimen with soap and water.
Pyrargyrite is very similar to Proustite, and forms a series with it. Pyrargyrite is the antimony-rich member, and Proustite is the arsenic-rich member. It is often not possible to visually distinguish these two minerals from each other. Pyrargyrite is the more common of this series, although good crystals of both these minerals are difficult to come across. Most good material in collections today are from closed, historical localities.
Pyrargyrite is named from the Greek words Pyr, "Fire" in allusion to the color of this mineral, and Argyros, meaning silver, describing its silver content. Hide
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Pyrite is sometimes called i Fools Gold i because of its similarity in color and shap... More
Pyrite is sometimes called Fools Gold because of its similarity in color and shape to Gold. In the old mining days, Pyrite was sometimes mistaken for Gold, as they frequently occur together, although Gold and Pyrite can very easily be distinguished by simple observation and testing of characteristics. Pyrite occurs in numerous shapes and habits. The smaller crystal aggregates may give off a beautiful glistening effect in light, and the larger crystals may be perfectly formed, including fascinating cubes, penetration twins, and other interesting crystal forms. The perfect cubes of Pyrite embedded in a matrix from the famous Spanish mines are especially treasured among collectors. Many of these specimens have fallen out of the matrix and have been repaired by having them glued back into the matrix. Pyrite has the same chemical formula as the rarer mineral Marcasite, but it crystallizes in a different crystal system, thereby classifying it as a separate mineral species. Aggregates of iron sulfide (FeS 2) where the crystal structure cannot be determined without complex analyzing material may be wrongly labeled by dealers. Some Pyrite specimens are labeled as Marcasite, and some Marcasite specimens as Pyrite.
For additional information, see the gemstone section on Pyrite. Hide
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div Pyrolusite is the most common manganese mineral. It is one of several manganese o... More
Pyrolusite is the most common manganese mineral. It is one of several manganese oxide minerals, which are all dark gray to black in color and may be very difficult to distinguish from one another, especially when in massive form. Wad is a term used to describe a combination of several unidentified manganese oxides, which may include a combination of Pyrolusite, Manganite, Psilomelane, and Romanechite.
Pyrolusite is known for its finely fibrous acicular crystal habits. These forms are usually sooty and will likely smudge the hands when touched.
Pyrolusite is named from a combination of the Greek words "Pyr" - fire, and "Louein" - to wash, since this mineral was once used as an agent to remove green and brown tints during the manufacture of glass.
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Pyromorphite is a member of the Apatite group , a group of isomorphous hexagonal mine... More
Pyromorphite is a member of the Apatite group, a group of
isomorphous hexagonal minerals. It is very similar in structure
and appearance to Mimetite, and may be partially replaced
by it. In fact, sometimes Pyromorphite and Mimetite are virtually
indistinguishable from each other and may be wrongly labeled as the
other. Hide
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Pyrope is a member of the Garnet group, and it makes a popular dark red gemstone. Pyr... More
Pyrope is a member of the Garnet group, and it makes a popular dark red gemstone. Pyrope is often free of flaws with good transparency, making it an important jewelry gemstone. Pyrope is much rarer than its Almandine counterpart, but it is generally more transparent and has less flaws than Almandine. A well-known environment of Pyrope is kimberlite pipes, where it can be associated together with Diamonds. Hide
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Pyrophyllite is isomorphous with the common mineral Talc , but has aluminum in place ... More
Pyrophyllite is isomorphous with the common mineral Talc, but has aluminum in place of the magnesium. It is very similar to Talc, with very similar properties and habits. However, it has distinct radiating crystal aggregates which easily identify it. Pyrophyllite is named after the Greek words " pyr" - "fire" and " phyllon" - leaf, regarding its property to exfoliate into fan shapes upon heating. Hide
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Pyroxmangite is a rare high temperature polymorph of the mineral Rhodonite . Its appe... More
Pyroxmangite is a rare high-temperature polymorph of the mineral Rhodonite. Its appearance is almost identical to Rhodonite, and only complex scientific tests can distinguish the two minerals. Hide
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Pyrrhotite is unusual in that it maintains a variable iron content, as reflected in i... More
Pyrrhotite is unusual in that it maintains a variable iron content, as reflected in its odd chemical formula. The variability is formed by deficiencies of iron in its chemical structure, which is also responsible for its magnetic properties. Greater deficiency of iron is responsible for stronger attraction to magnetic fields. If the mineral lacks any iron deficiencies, it is no longer Pyrrhotite, but a rare, non-magnetic mineral called Troilite. (Troilite usually originates from meteoric sources.)
The variation of iron in Pyrrhotite's structure is also responsible for more than one crystal symmetry type, allowing it to form in both hexagonal and monoclinic symmetries. Multiple crystal symmetries should technically classify Pyrrhotite as a mineral group rather than a single mineral, but a sub-classification is rarely made due to polytypes appearing similar and perhaps even combined within individual specimens. Though most Pyrrhotite specimens are stable, some tend to crumble in collections.
Pyrrhotite is commonly pseudomorphed by Pyrite, with complete replacement of the Pyrhottite by sparkling Pyrite crystals. Pyrrhotite is named from the Greek word pyrrhos, which means "color of fire". This is despite the fact that the usual color of Pyrrhotite is a bronze color rather than red; however its tarnish may have hints of sparkling red.
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