ORE DEP (WEATHERING) Flashcards
Deposit restricted to ultramafic rocks of the various ophiolite belts where climatic conditons and phyriographic favor laterization processes
Laterites
Division of laterite with:
?High Fe
?Low Ni, Co, Mg and Si
Limonite
Divison of Laterite with:
?High Ni, Co, Mg
?Low Fe
Garnierite
A-Type Nickel Laterite Ore which contains Ni-Bearing Silicates in weathered Rocks
Saprolite
Ni Serpentine in which Mg»Ni, Fe
Garnierite
Ni replaces Mg in Garnierite
Noumeite
Ni replaces Fe in Garnierite
Nepouite
Ni Bearing Smectite
Pimelite
B-type Nickel Laterite in which Ni is adsorbed onto and included in geothites and other hydrous Fe Oxides
Laterite Ore
Controls on Ni Laterite
?Stable Tropical Climate
?Broad Outcrops of UM rocks
?20 deg slope
?Plateu Topog w/ generates stable, slow subsruface water movement
?Time
Example of Ni-Laterite in the Phi
Riotuba Palawan
Berong, Palawan
Taganito, Surigao del N (Taas)
Hinatuan, Surigao del S
Al-rich laterite , high in Al2O low in SiO2 and Fe2O3 and forms when silica in aluminum bearing rocks (High felds) is washed away or leachd
Bauxite
Three Hydroxides which combines to form Bauxite
Diaspore Alpha AlO (OH)
Boehmite Beta AlO (OH)
Gibbsite Al (OH)3
favorable bedrocks for bauxite formation
Syenites and
Argilleaceous Carbonate rocks
Other properties of Bauxite
Earthy and dull Laster can look like soil or clay
Reddishbrown, white, Tan to tan-yellow
Carbonate Bauxites
Europe and Jamaica above carbonates
Lateritic Bauxites
Tropical Countries above silicic rocks
Whre is the zone of highest Al Content in Bauxites?
Below a ferruginous surface layers
Weathering of Cu-Bearing mineralization wherein a small percentage of Cu can be leahed from Large volume or rock and can be redeposited as a higher grade deposit in a smaller volume of rocks provided that the conditions are favorable
Supergene Cu-Enrichment
Favorable Conditions for Supergene Enrichment
?Protore is porous and permeable to meteoric water
?Protore contains abundant Pyrite to produce oxidixing acids - phyllic zones
?Protore contains ACID-Soluble ore metal bearing minerals
?Precipitative Envi - Arid Envi
Examples of Supergene Enrichment of PCD in Ard Envi
Chiquimata
El Salvador
Levels of Supergene Enrichment
OXIDIZED ZONE
1)Gossan - Hydrated Iron Oxides
2)Leached Zones - Hydroxyl Carbonates
3) Oxidized Zone - Cuprite, Crysocolla
-Water Table-
REDUCED ZONE
1)Seconary Sulfide Enrichments - Cpy, Covel, Born
2) Protore - Pyr + Chlcopyr
