Descriptive Mineralogy Native...

Descriptive Mineralogy

Native Elements:Pure elements that occur

as minerals

Classification of the Minerals• Non-Silicates

– Native Elements– Halides– Sulfides– Oxides– Hydroxides– Carbonates– Sulfates– Phosphates

• Silicates– Orthosilicates– Sorosilicates– Cyclosilicates– Chain Silicates– Layer Silicates– Tektosilicates

Native Elements

Native Elements: Metals

• Fe, Co, Ni: Meteorites• Platinum Group: (Ru, Rh, Pd, Os, Ir, Pt):

Mafic Igneous Rocks• Coinage metals: Cu, Ag, Au

– Cu, Ag: Supergene Enrichments (SulfideOxidation)

– Au: Low Temperature Hydrothermal, Placer

Native Iron: Meteorites

Native Iron: MeteoritesWidmanstätten Pattern

Iron-Nickel Phase Diagram

Platinum Group MetalsRu, Rh, Pd, Os, Ir, Pt

• Strongly siderophile elements• Enriched in Fe meteorites• Found in layered mafic intrusions

– Bushvelt Complex (South Africa)– Stillwater Complex (Montana)– Skaergaard Complex (Greenland)

Bushvelt: Layered Gabbroic Intrusion

Bushvelt: Layered Gabbroic Intrusion

Skaergaard: Layered Gabbroic Intrusion

Skaergaard: Layered Gabbroic Intrusion

Skaergaard: Layered Gabbroic Intrusion

Native Elements: Cu, Ag, Au• Cu and Ag: Supergene Enrichment

– Oxidation of Cu, Ag sulfides inunsaturated zone

– Precipitation of metal, oxides andcarbonates at water table

• Ag and Au: hydrothermal– Native metals and tellurides

• Au: placer– oxidized hydrothermal

Supergene Copper

Hydrothermal Silver

Hydrothermal Gold

Hydrothermal Gold

Native Elements: non metals

• Carbon:– Graphite: Metamorphic Rocks– Diamond: Kimberlites

• Sulfur (+Se):– Salt Domes (Sulfate reduction),– Volcanos (H2S oxidation)

• Tellurium (Te) Tellurideoxidation

Native Elements: Carbon

• Graphite (Low Pressure)– Metamorphosed Organic-rich sediments

• Diamond (High Pressure >100km)– Kimberlites– Placers from kimberlites

Native Elements: Diamond

Native Elements: Diamond

Kimberley Mine 1875

Native Elements: Sulfur

• Fumaroles (Volcanic hydrothermal vents)– Oxidation of H2S

• Salt dome cap rocks– Sulfate reduction by petroleum

Fumarole Sulfur: Nysseros

Native Elements