pyrrhotite

Pyrrhotite is an unusual iron sulfide mineral with a variable iron content: Fe(1-x)S (x = 0 to 0.2). The FeS endmember is known as troilite. Also called magnetic pyrite because the color is similar to pyrite and it is weakly magnetic, the magnetism increases as the iron content decreases.Pyrrhotite is odd also because it has two crystal symmetries. When pyrrhotite is high in iron and the formula is closer to true FeS the structure is hexagonal. But, when it is low in iron, the structure is monoclinic. Both symmetries occur together in the same specimen.The name is derived from Greek pyrrhos, flame-colored.
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Noun
1. a brownish iron sulfide mineral FeS having weak magnetic properties
(synonym) pyrrhotine, magnetic pyrites
(hypernym) mineral

(n.)
A bronze-colored mineral, of metallic luster. It is a sulphide of iron, and is remarkable for being attracted by the magnet. Called also magnetic pyrites.
  

General Information:
 Chemical Formula:
Fe(1-x)S (x=0-0.17)
 Composition:
(Molecular Weight = 85.12 gm)
Iron 62.33 % Fe
Sulfur 37.67 % S 
 Empirical Formula:
Fe2+0.95S
 Environment:
Wide spread occurrences in igneous and metamorphic rocks.
 Locality:
Sudbury, Ontario, Canada and Santa Eulalia, Chihuahua, Mexico.
 Name Origin:
From the Greek, phrrhotes, "redness," in allusion to color.
Physical Properties:
 Cleavage:
[0001] Imperfect, [1120] Imperfect
 Color:
bronze, bronze red, or dark brown.
 Density:
4.58 - 4.65, Average = 4.61
 Diaphaniety:
Opaque
 Habits:
Tabular - Form dimensions are thin in one direction., Platy - Sheet forms (e.g. micas)., Massive - Granular - Common texture observed in granite and other igneous rock.
 Hardness:
3.5-4 - Copper Penny-Flourite
 Luminescence:
None.
 Luster:
Metallic
 Streak:
gray black
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