Composition: Iron Sulfide
Crystal System: isometric
Hardness: 6 - 6.5
Specific Gravity: apx 5.1+
Streak: greenish black
Color: brassy yellow
Cleavage: very indistinct
Associated Minerals: calcite, fluorite,
galena, gold, quartz, sphalerite and many others
Iron sulphide (46.6% Fe 53.4% S)
Bravoite is the name given to a nickel-rich iron sulfide. It is closely
related to pyrite but contains up to 20% nickel. Pyrite's structure is
analogous to galena's structure with a formula of PbS.
When tarnished pyrite might be confused with chalcopyrite, but it is
harder and more yellow. Pyrite is difficult to distinguish from marcasite
when a lack of clear indicators exists. pyrite is more slowly soluble
in nitric acid than marcasite, giving a clear solution. Pyrite and Marcasite are polymorphs because both have the same chemical formula, FeS2,
but both have different atomic structures. Pyrite has an isometric,
cubic structure and Marcasite has an orthrohombic structure. Pyrite of
coarse is harder than gold, and very brittle.
There are other shiny brassy yellow minerals that might be mistaken
for gold. But pyrite is the most common and the most often mistaken for
gold. Hence The name "Fools Gold". It also has a beautiful luster
and interesting crystals. Pyrite is found in almost every possible environment,
there for it has many forms and varieties. Pyrite is a frequent associate
of all sorts of metal ores. In addition, it forms concretionary masses
in sedimentary rocks. It is common in coal, and in slates and other metamorphic
rocks. Pyrite can be altered to an oxide of iron, becoming limonite. Although
pyrite is more stable than marcasite, pyrite is easily oxidized. Veins
of pyrite are commonly found with overlaying cellular deposits of limonite called gossan. The ready oxidation of pyrite both disintegrates and stains.
Making rocks containing pyrite ineffective for any structural purposes.
Pyrite is often crystallized, most frequently in striated cubes,
less commonly in pyritohedrons or octahedrons. Massive pyrite is common.
Crystal Habits include the cube, octahedron and pyritohedron (a dodecahedron
with pentagonal faces) and crystals with combinations of these forms.
Good interpenetration twins called iron crosses are rare. Found commonly
in nodules. A flattened nodular variety called "Pyrite Suns" or "Pyrite
Dollars" is popular in rock shops. Also massive, reniform and replaces
other minerals and fossils forming pseudomorphs or copies.
Fuses easily. Becomes magnetic and gives off SO2 fumes. Insoluble in HCl, but a fine powder will dissolve in concentrated
Fine specimens have been found throughout the world.
Some of the more well know locations are Leadville, Colorado. Well developed
crystal groups were found at Park City, Utah. Misshapen octahedral crystals
containing 0.2% arsenic were found at French Creek, Pennsylvania. Other
USA locations include Illinois and Missouri to name just a few. Complex, perfect crystals come from Elba, Italy. Falun, Sweden, yielded, a pyrite
rich in cobalt. Many specimens today are coming from Peru. The specimens
from Peru seem to be brighter and tarnish less easily. We have seen many
mixed specimens from Mexico containing pyrite. Other famous localities
include Germany; Russia; Spain; and South Africa along with many others.
A very minor ore of sulfur for sulfuric acid, used in
jewelry under the trade name "marcasite" and as mineral specimens. Although
pyrite is common and contains a high percentage of iron, it has never been used as a significant source of iron. However new technologies have opened the dor for it's use as an Iron Ore. But for now Iron oxides such
as hematite and magnetite, are the primary iron ores. Pyrite is not as
economical as these ores possibly due to their tendency to form larger
concentrations of more easily mined material. Pyrite would be a potential
source of iron if these ores should become scarce. Pyrite frequently has
rich trace amounts of gold which can make it an important gold ore.
FACTS & HISTORY:
Name Origin: Greek, pyrite's lithos meaning "stone which strikes fire,"
in reference to the spark produced when iron is struck with a piece of
During WW II, the demand for sulfur kept increasing while the amount of
native sulfur mined in North America kept decreasing. Native sulfur mines
were becoming exhausted, making pyrite an attractive alternative economically.
One large deposit near Ducktown, Tennessee began mining pyrite, pyrrohite
and pentlandite exclusively for their sulfur contents.
Pyrite was first used to make sulfuric acid around 1000 AD. sulfuric acid is a very important acid in industry today. It
is used to process almost any type of product you can think of.
Pyrite is commonly associated with quartz and fine mineral specimen
of pyrite on quartz or quartz on pyrite, seem to be rather abundant. Pyrite
inclusions in quartz on the other hand, seem to be quite rare. Brazil has quartz included with pyrite. This quartz generally has
massive looking little chunks of pyrite floating in it. Although some
of it displays nice little cubes floating in it too. Iron oxide also commonly
graces this material. Giving it interesting and beautiful yellow, orange
and reddish orange streaks and clouds
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