Minerals: Sulfides

Minerals are defined by five criteria: 1. Naturally Occurring, 2. Inorganic, 3. Solid, 4. Defined Chemical (Atomic) Formula, and 5. A unique set of physical properties.

Sulfides – are chemical compounds in which sulfur has combined with metallic and semi-metallic elements. Sulfides are very important ores of lead, zinc, iron, and copper. They form in hydrothermal veins below the water table as they are easily oxidizedto sulfates.

Specimen: Galena
Classification: Sulfide
Chemical Composition: PbS
Crystal structure: Cubic
Hardness: 2.5
Specific Gravity: 7.58
Luster: Metallic
Cleavage: Perfect cube
Fracture: Subconchoidal
Source: Forms in hydrothermal veins. Often occures with quartz, sphalerite, calcite, pyrite, and flourite.
Uses: Lead ore

 

Specimen: Galena cluster
Classification: Sulfide
Chemical Composition: PbS
Crystal structure: Cubic
Hardness: 2.5
Specific Gravity: 7.58
Luster: Metallic
Cleavage: Perfect cube
Fracture: Subconchoidal
Source: Forms in hydrothermal veins. Often occures with quartz, sphalerite, calcite, pyrite, and flourite.
Uses: Lead ore

 

Specimen: Galena
Classification: Sulfide
Chemical Composition: PbS
Crystal structure: Cubic
Hardness: 2.5
Specific Gravity: 7.58
Luster: Metallic
Cleavage: Perfect cube
Fracture: Subconchoidal
Source: Forms in hydrothermal veins. Often occures with quartz, sphalerite, calcite, pyrite, and flourite.
Uses: Lead ore

 

Specimen: Galena cubes
Classification: Sulfide
Chemical Composition: PbS
Crystal structure: Cubic
Hardness: 2.5
Specific Gravity: 7.58
Luster: Metallic
Cleavage: Perfect cube
Fracture: Subconchoidal
Source: Forms in hydrothermal veins. Often occures with quartz, sphalerite, calcite, pyrite, and flourite.
Uses: Lead ore

 

Specimen: Stibnite
Classification: Sulfide
Chemical Composition: Sb2S3
Crystal structure: Orthorhombic
Hardness: 2
Specific Gravity: 4.63 to 4.66
Luster: Metallic
Cleavage: Perfect 
Fracture: Uneven to subconchoidal
Source: Forms in low temperature hydrothermal veins and hot mineral springs.
Uses: Antimony ore

 

Specimen: Pyrrhotite
Classification: Sulfide
Chemical Composition: Fe1−xS (x = 0 to 0.2)
Crystal structure: Monoclinic
Hardness: 3.5 to 4.5
Specific Gravity: 4.53 to 4.77
Luster: Metallic
Cleavage: None
Fracture: Subconchoidal to uneven
Source: Commonly forms in magnetic igneous deposits, particularly basic/mafic or ultrabasic/ultramafic.
Uses: Collected

 

Specimen: Pyrite cluster
Classification: Sulfide
Chemical Composition: FeS2
Crystal structure: Cubic
Hardness: 6 to 6.5
Specific Gravity: 5.0
Luster: Metallic
Cleavage: Indistinct
Fracture: Conchoidal to even
Source: Forms in hydrothermal veins and can be found  in igenous, sedimentary, and metamorphic rocks.
Uses: Source of sulphur dioxide and sulphuric acid.

 

Specimen: Pyrite cluster
Classification: Sulfide
Chemical Composition: FeS2
Crystal structure: Cubic
Hardness: 6 to 6.5
Specific Gravity: 5.0
Luster: Metallic
Cleavage: Indistinct
Fracture: Conchoidal to even
Source: Forms in hydrothermal veins and can be found  in igenous, sedimentary, and metamorphic rocks.
Uses: Source of sulphur dioxide and sulphuric acid.

 

Specimen: Pyrite cluster
Classification: Sulfide
Chemical Composition: FeS2
Crystal structure: Cubic
Hardness: 6 to 6.5
Specific Gravity: 5.0
Luster: Metallic
Cleavage: Indistinct
Fracture: Conchoidal to even
Source: Forms in hydrothermal veins and can be found  in igenous, sedimentary, and metamorphic rocks.
Uses: Source of sulphur dioxide and sulphuric acid.

 

Specimen: Pyrite cube in marl matrix
Classification: Sulfide
Chemical Composition: FeS2
Crystal structure: Cubic
Hardness: 6 to 6.5
Specific Gravity: 5.0
Luster: Metallic
Cleavage: Indistinct
Fracture: Conchoidal to even
Source: Forms in hydrothermal veins and can be found  in igenous, sedimentary, and metamorphic rocks.
Uses: Source of sulphur dioxide and sulphuric acid.

 

Specimen: Pyrite cube in marl matrix
Classification: Sulfide
Chemical Composition: FeS2
Crystal structure: Cubic
Hardness: 6 to 6.5
Specific Gravity: 5.0
Luster: Metallic
Cleavage: Indistinct
Fracture: Conchoidal to even
Source: Forms in hydrothermal veins and can be found  in igenous, sedimentary, and metamorphic rocks.
Uses: Source of sulphur dioxide and sulphuric acid.

 

Specimen: Pentameral pyrite crystal
Classification: Sulfide
Chemical Composition: FeS2
Crystal structure: Cubic
Hardness: 6 to 6.5
Specific Gravity: 5.0
Luster: Metallic
Cleavage: Indistinct
Fracture: Conchoidal to even
Source: Forms in hydrothermal veins and can be found  in igenous, sedimentary, and metamorphic rocks.
Uses: Source of sulphur dioxide and sulphuric acid.

 

Specimen: Pyrite/Marcasite “sun disk”
Classification: Sulfide
Chemical Composition: FeS2
Crystal structure: Orthorhombic
Hardness: 6 to 6.5
Specific Gravity: 4.92
Luster: Metallic
Cleavage: Distinct
Fracture: Uneven
Source: Commonly forms from acidic solutions permeating beds of limestone, shale, and chalk.
Uses: Collected

 

Specimen: Marcasite cluster
Classification: Sulfide
Chemical Composition: FeS2
Crystal structure: Orthorhombic
Hardness: 6 to 6.5
Specific Gravity: 4.92
Luster: Metallic
Cleavage: Distinct
Fracture: Uneven
Source: Commonly forms from acidic solutions permeating beds of limestone, shale, and chalk.
Uses: Collected

 

Specimen: Chalcopyrite
Classification: Sulfide
Chemical Composition: CuFeS2
Crystal structure: Tetragonal
Hardness: 3.5 to 4
Specific Gravity: 4.3 to 4.4
Luster: Metallic
Cleavage: Poor
Fracture: Uneven to Chonchoidal
Source: Commonly forms sulfide ore deposits and hydrothermal veins.
Uses: Copper ore

 

Specimen: Bornite “peacock ore”
Classification: Sulfide
Chemical Composition: Cu5FeS4
Crystal structure: Cubic
Hardness: 3
Specific Gravity: 5.0 to 5.1
Luster: Metallic
Cleavage: Very poor
Fracture: Uneven to Chonchoidal
Source: Commonly forms in hydrothermal veins.
Uses: Collector’s stone

 

Specimen: Marmatite (Black variety of Sphalerite
Classification: Sulfide
Chemical Composition: (Zn,Fe)S
Crystal structure: Cubic
Hardness: 3.5 to 4
Specific Gravity: 3.9 to 4.1
Luster: Metallic
Cleavage: Perfect
Fracture: Chonchoidal
Source: Commonly forms in hydrothermal veins. Commonly found with quartz, galena, pyrite, dolomite, calcite, and barite.
Uses: Industrial uses brass and batteries

 

Specimen: Sphalerite “blende” or “black jack”
Classification: Sulfide
Chemical Composition: (Zn,Fe)S
Crystal structure: Cubic
Hardness: 3.5 to 4
Specific Gravity: 3.9 to 4.1
Luster: Metallic
Cleavage: Perfect
Fracture: Chonchoidal
Source: Commonly forms in hydrothermal veins. Commonly found with quartz, galena, pyrite, dolomite, calcite, and barite. 
Uses: Industrial uses brass and batteries

 

Specimen: Sphalerite “blende” or “black jack”
Classification: Sulfide
Chemical Composition: (Zn,Fe)S
Crystal structure: Cubic
Hardness: 3.5 to 4
Specific Gravity: 3.9 to 4.1
Luster: Metallic
Cleavage: Perfect
Fracture: Chonchoidal
Source: Commonly forms in hydrothermal veins. Commonly found with quartz, galena, pyrite, dolomite, calcite, and barite. 
Uses: Industrial uses brass and batteries

 

Specimen: Sphalerite cluster
Classification: Sulfide
Chemical Composition: (Zn,Fe)S
Crystal structure: Cubic
Hardness: 3.5 to 4
Specific Gravity: 3.9 to 4.1
Luster: Metallic
Cleavage: Perfect
Fracture: Chonchoidal
Source: Commonly forms in hydrothermal veins. Commonly found with quartz, galena, pyrite, dolomite, calcite, and barite.
Uses: Industrial uses brass and batteries

 

Specimen: Sphalerite cluster on matrix
Classification: Sulfide
Chemical Composition: (Zn,Fe)S
Crystal structure: Cubic
Hardness: 3.5 to 4
Specific Gravity: 3.9 to 4.1
Luster: Metallic
Cleavage: Perfect
Fracture: Chonchoidal
Source: Commonly forms in hydrothermal veins. Commonly found with quartz, galena, pyrite, dolomite, calcite, and barite.
Uses: Industrial uses brass and batteries

 

Specimen: Realgar “ruby sulphur” “ruby of arsenic”
Classification: Sulfide
Chemical Composition: As4S4 or AsS
Crystal structure: Monoclinic
Hardness: 1.5 to 2
Specific Gravity: 3.56
Luster: Resinous to greasy
Cleavage: Good
Fracture: Conchoidal
Source: Commonly forms in low  hydrothermal veins and around hot springs.
Uses: Historically fireworks before powdered metals.

 

Specimen: Realgar “ruby sulphur” “ruby of arsenic”
Classification: Sulfide
Chemical Composition: As4S4 or AsS
Crystal structure: Monoclinic
Hardness: 1.5 to 2
Specific Gravity: 3.56
Luster: Resinous to greasy
Cleavage: Good
Fracture: Conchoidal
Source: Commonly forms in low  hydrothermal veins and around hot springs.
Uses: Historically fireworks before powdered metals.

 

Specimen: Realgar “ruby sulphur” “ruby of arsenic”
Classification: Sulfide
Chemical Composition: As4S4 or AsS
Crystal structure: Monoclinic
Hardness: 1.5 to 2
Specific Gravity: 3.56
Luster: Resinous to greasy
Cleavage: Good
Fracture: Conchoidal
Source: Commonly forms in low  hydrothermal veins and around hot springs.
Uses: Historically fireworks before powdered metals.

 

Specimen: Orpiment
Classification: Sulfide
Chemical Composition: As2S3
Crystal structure: Monoclinic
Hardness: 1.5 to 2
Specific Gravity: 3.4 to 3.5
Luster: Resinous, pearly on cleavage surface
Cleavage: Perfect
Fracture: Uneven
Source: Commonly forms in low  hydrothermal veins, crust deposits, and around hot springs.
Uses: Historically pigment and medicine.

 

Specimen: Orpiment
Classification: Sulfide
Chemical Composition: As2S3
Crystal structure: Monoclinic
Hardness: 1.5 to 2
Specific Gravity: 3.4 to 3.5
Luster: Resinous, pearly on cleavage surface
Cleavage: Perfect
Fracture: Uneven
Source: Commonly forms in low  hydrothermal veins, crust deposits, and around hot springs.
Uses: Historically pigment and medicine.

 

Specimen: Molybdenite
Classification: Sulfide
Chemical Composition: MoS2
Crystal structure: Trigonal/Hexagonal
Hardness: 1 to 1.5
Specific Gravity: 4.62 to 5.06
Luster: Metallic
Cleavage: Perfect basal
Fracture: Uneven
Source: Forms in hydrothermal veins and granitic rocks.
Uses: Ore of molybdenum, an iron alloy

 

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Data: Pellant, Chris. Smithsonian Handbooks: Rocks and Minerals, The clearest recognition guides avaiable. A Dorling Kindersley Book.

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