14Natives

Transcript 14Natives

Descriptive Mineralogy Native Elements:

Pure elements that occur as minerals

• Classification of the Minerals Non-Silicates • Silicates – – – – – – – – Native Elements Halides Sulfides Oxides Hydroxides Carbonates Sulfates Phosphates – – – – – – 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 (Sulfide Oxidation)

–

Au: Low Temperature Hydrothermal, Placer

Native Iron: Meteorites

Native Iron: Meteorites Widmanstätten Pattern

Iron-Nickel Phase Diagram

• • • Platinum Group Metals Ru, 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

Skaergaard: Layered Gabbroic Intrusion

Native Elements: Cu, Ag, Au • • • Cu and Ag: Supergene Enrichment – – Oxidation of Cu, Ag sulfides in unsaturated zone Precipitation of metal, oxides and carbonates at water table Ag and Au: hydrothermal – Native metals and tellurides Au: placer – oxidized hydrothermal

Supergene Copper

Hydrothermal Silver

Hydrothermal Gold

Native Elements: non metals • • • Carbon: – Graphite: Metamorphic Rocks – Diamond: Kimberlites Sulfur (+Se): – – Salt Domes (Sulfate reduction), Volcanos (H 2 S oxidation) Tellurium (Te) Telluride oxidation

Native Elements: Carbon • • Graphite (Low Pressure) – Metamorphosed Organic-rich sediments Diamond (High Pressure >100km) – – Kimberlites Placers from kimberlites

Native Elements: Diamond

Kimberley Mine 1875

Native Elements: Sulfur • Fumaroles (Volcanic hydrothermal vents) – Oxidation of H 2 S • Salt dome cap rocks – Sulfate reduction by petroleum

Fumarole Sulfur: Nysseros

In the caps of salt domes, gypsum (CaSO 4 2H 2 O) is reduced to native sulfur

Native Elements

14Natives

Transcript 14Natives

Descriptive Mineralogy Native Elements:

Directory