W9 Ore Fluids and Ore Minerals

Question 1

hydrothermal circulation

Answer 1

Convection cycle
cold dense water flows down , red hot water flows up
often release sulphur or sulphides

Question 2

Ore definition

Answer 2

a naturally occurring mineral aggregate from which an elemental metal or a naturally occurring alloy may be extracted and refined, for PROFIT

Question 3

Gangue definition

Answer 3

the non-economic fraction of an orebearing mineral assemblage

Question 4

common gangue minerals

Answer 4

iron pyrites, quartz, calcite, orthoclase
precipitated by fluids that flow along fractures
make fluid shapes, coloured likes or zones and crytslas growing away

Question 5

Native metals

Answer 5

metals that can be found in nativeform and used /sold right away
such as gold platinum copper zinc etc

Question 6

Igneous Ore Deposits: Copper Porphyries

Answer 6

volcanic system → materials move around to hottest zone → high temp fluids in hottest zone, zonation between hot materials in center and cool materials outwards –> deceminated (distributed in matrix of rock) → a lot of copper from this deposit

Question 7

Igneaous Ore Deposits: Volcanic Ores: Kuroko Deposits

Answer 7

shallower than porphyries
associated with supra-subduction volcanics
• massive sulphide deposits

Question 8

Igneaous Ore Deposits: : Hydrothermal Veins

Answer 8

volatiles derived from igneous rocks Metal + ‘salts’ carried in aqueous solutions

Question 9

Vein definition

Answer 9

Vein - a well defined sheet of mineralisation, infill fissures or fault zones

Question 10

Hydrothermal Veins . aufteilung

Answer 10

Epithermal Veins with a Temp less than 300 degrees C
major precius metal deposits (gold)
source of fluids: Dominantly meteoric waters + volcanic volatiles
Mesothermal Veins, midfdle temp
Hypothermal, more than 400C so very hot magmatic volatiles

Question 11

Sediment hosted ore deposits: Placer Deposits

Answer 11

Chemically inert ores and other heavy minerals (i.e. gemstones) are concentrated in clastic sediments during erosion and transportation

Question 12

Sediment hosted ore deposits:: Sedimentary Iron stones

Answer 12

for iron ores

Question 13

Ores assosciated with mid ocean ridge hydrothermal activity

Answer 13

Cyprus type ores

Volcanic Massive Sulphide (VMS) Deposits

Question 14

Ores derived from seafloorhydrothermal vents

Answer 14

black smoker

Chimneys are composed of Cu- & Fe-sulphides; they collapse to form massive sulphide mounds on the seafloor

Question 15

Gossan is

Answer 15

weathered surface outcrop of ore deposits