Showing posts with label Mineral exploration. Show all posts
Showing posts with label Mineral exploration. Show all posts
Sunday, June 14, 2015
Monday, May 25, 2015
What Does it Cost?
Exploration & Mining from Ore
to Metal …. What does it Cost?!!
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A Comment by
Usually 5 years of a company's
time the financial cost depends on
what you are looking for, where your are
looking and what you end up finding?
|
Saturday, April 25, 2015
Classification of Mineral Deposits
Depth of Occurrence
Exposed to surface
Mineral
deposits like iron ore, bauxite, chromite, copper, limestone and magnesite are
exposed to the surface and easy
to explore. Although most of the significant exposed ore
deposits, namely, Example Outside
the Sterling Hill Mine are
exposures of the weathered surface of the zinc ore body in the Passaic
Pit. Calamine (zinc silicate) was mined in this oxidized portion of
the ore body. Canon City, USA.
Shallow Depth
Deposits
like base
metals, coal and gypsum are covered by altered
oxidized capping or exist
at shallow depth or under thick overburden of bedrock. The
deposits are Cerro de Maimon
copper-gold deposit at Dominican
Republic, Geochemical prospecting
and ground geophysical survey will be helpful for
discovery of deposits at shallow depth.
Deep-Seated Hidden Deposit
Deep-seated hidden deposits will be the future target of
mineral exploration. The key exploration procedures suitable
for discovery of an
orebody at a depth range of 300-700 m
require clear understanding of regional structure, applications
of high penetrative geophysical methods and
interpretation by
simulation tools to identify, describe and delineate. Exploration for such deposits is expensive and associated with considerable economic risk. The
high costs result from
the necessity of expensive
instrumentation and extensive
drilling at depth. Ex. The hidden poly-metallic
deposits discovered in the past are Neves Corvo copper-zinc-tin, Portugal, at 330-1000
m depth, and
Sindesar
Khurd zinc
lead-silver at 130 m depth, India.
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| Exposed to surface,Shallow depth, Deep-seated hidden deposit |
Friday, April 24, 2015
Economic Ore forming Mineral Deposits
List of Common Metallic and Nonmetallic OFM and Uses 4
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| List of Common Metallic and Nonmetallic OFM and Uses 4 |
Economic Ore forming Mineral Deposits
List of Common Metallic and Nonmetallic OFM and Uses 3
 |
| List of Common Metallic and Nonmetallic OFM and Uses 3 |
Economic Mineral Deposits
List of Common Metallic and Nonmetallic OFM and Uses 2
List of Common Metallic and Nonmetallic OFM and Uses 2
List of Common Metallic and Nonmetallic OFM and Uses 1
List of Common Metallic and Nonmetallic OFM and Uses 1
List of Common Metallic and Nonmetallic OFM and Uses
Economic Mineral Deposits and Host Rocks
Common Economic Minerals
A mineral can be termed economic or
uneconomic depending on its industrial use. The mineral quartz is economic as
silica sand used in glass or optical industry. The same mineral is uneconomic
when it hosts gold as auriferous quartz vein or occurs as a constituent of
rocks hosting copper, zinc and iron ore. It is then processed and discarded as gangue, tailing or waste. The ore deposits
are generally composed of a main product,
one or more by-products and trace
elements such
as zinc-lead-silver,
copper-gold, chromium-nickel platinumpalladium.
Sometimes a single mineral forms the valuable deposit such as calcite in marble. The same
mineral can be
designated as metallic or industrial depending on
its use. Bauxite ore is “metallic” when aluminum is produced and “industrial” when used directly for refractory
bricks and abrasives.
An ore deposit can be composed of metallic and nonmetallic minerals, mined together and
processed to produce separate
products. An example can be Bou Jabeur deposit,
Tunisia, containing galena and sphalerite along
with fluorite and barite.
The economic minerals occur in various
forms such as native elements
to compounds of oxide, carbonate, silicate,
sulfide, sulfate, sulfosalts, phosphate etc.
Common Economic Minerals
Economic Mineral Deposits and Host Rocks
What a Concentration is Needed to Make an Economic Deposit ?
A mineral deposit becomes economic when it has a profitable commercial value attached to it. The concentration of minerals or metals in deposits vary widely and range from few parts per million (1-100 g/t or ppm) in noble metals like platinum, palladium, gold, silver to low percentage (1-10%) for copper, zinc, lead, and higher grade (40-60%) for aluminum, chromium, iron and aggregates.
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| What a Concentration is Needed to Make an Economic Deposit ? |
Thursday, April 23, 2015
Al Sukari Gold Mine
Al Sukari Gold Mine
 |
| Al Sukari Gold Mine |
Location: Marsa Alam, Red
Sea, Egypt.
Products: Gold.
Owner: Centamin.
Geology of the Sukari gold mine area
The mine occurs within a Late Neoproterozoic
granitoid (Arslan 1989; Harraz 1991) that intruded older volcanosedimentary successions
and an ophiolitic assemblage, both known as Wadi Ghadir me´lange (El Sharkawi
and El Bayoumi 1979). The volcanosedimentary succession is composed of
andesites, dacites, rhyodacites, tuffs and pyroclastics. Magmatic rocks are of
calc-alkaline affinity (Akaad et al. 1995) and were formed in an island-arc setting
(El Gaby et al. 1990). The dismembered ophiolitic succession is represented by
a serpentinite at the base, followed upwards by a metagabbro-diorite complex and
sheeted dykes. Metagabbro-diorite rocks and serpentinites form lenticular
bodies (1–3 km2) as well as small bodies occur conformably scattered in the
volcanosedimentary arc assemblage (Harraz 1991). All rocks are weakly
metamorphosed (lower greenschist metamorphic facies), intensely sheared and
transformed into various schists along shear zones. Mineralized quartz veins
and talc-carbonate veinlets are common.
Type of Deposit
& Mineralization
The vein-type deposit is hosted in Late Neoproterozoic granite that
intruded island-arc and ophiolite rock assemblages. The vein-forming process is
related to overall late Pan-African shear and extension tectonics. At Sukari,
bulk NE– SW strike-slip deformation was accommodated by a local flower
structure and extensional faults with veins that formed initially at conditions
of about 300 C and 1.5–2 kbar. Gold is associated with sulfides in quartz veins
and in alteration zones. Pyrite and arsenopyrite dominate the sulfide ore
beside minor sphalerite, chalcopyrite and galena. Gold occurs in three distinct
positions: (1) anhedral grains (GI) at the contact between As-rich zones within
the arsenian pyrite; (2) randomly distributed anhedral grains (GII) and along
cracks in arsenian pyrite and arsenopyrite, and (3) large gold grains (GIII)
interstitial to fine-grained pyrite and arsenopyrite.
How the Gold is Extracted
Thousands of pounds of explosives, trucks and shovels as large as a house, and massive grinding
machines that can reduce hard rocks to dust are involved in the extraction process. In this way, Gold is extracted from one of the largest
open-air mines on the planet. The raw material excavated from the terraces in
the mine contains gold and arsenic in pyrite and arsenopyrite is a distinct
feature of the gold mineralisation at Sukari.
It is the Only
Open pit mine in Egypt.
Geology of the Sukari gold mine area
The mine occurs within a Late Neoproterozoic
granitoid (Arslan 1989; Harraz 1991) that intruded older volcanosedimentary successions
and an ophiolitic assemblage, both known as Wadi Ghadir me´lange (El Sharkawi
and El Bayoumi 1979). The volcanosedimentary succession is composed of
andesites, dacites, rhyodacites, tuffs and pyroclastics. Magmatic rocks are of
calc-alkaline affinity (Akaad et al. 1995) and were formed in an island-arc setting
(El Gaby et al. 1990). The dismembered ophiolitic succession is represented by
a serpentinite at the base, followed upwards by a metagabbro-diorite complex and
sheeted dykes. Metagabbro-diorite rocks and serpentinites form lenticular
bodies (1–3 km2) as well as small bodies occur conformably scattered in the
volcanosedimentary arc assemblage (Harraz 1991). All rocks are weakly
metamorphosed (lower greenschist metamorphic facies), intensely sheared and
transformed into various schists along shear zones. Mineralized quartz veins
and talc-carbonate veinlets are common.
The fresh rock is
leucocratic, coarse-grained and pink in color. It has a heterogeneous
mineralogical composition and ranges from monzogranite to granodiorite with dominant
quartz, plagioclase and potash feldspars and less abundant biotite. The Sukari
granitoid has a trondhjemitic affinity (Arslan 1989) and belongs to the ‘‘Younger
Granite Suite’’ of Akaad and Nowier (1980).
Harraz (1991)
argued for a transitional tectonic environment between within-plate,
volcanic-arc and syncollision granite fields. The age of the Sukari granitoid body
is poorly constrained (630–580 Ma, Harraz 1991) but documents Late Pan-African
magmatic activity in the area.
In the vicinity of
shear zones the granite is foliated, elsewhere, however, it has sharp intrusive
contacts against the older rocks. Along those shear zones serpentinite and
andesite is altered to listvenite rock (Khalaf and Oweiss 1993) that attains up
to 70 m in thickness and extends for several kilometers. At the intersection of
the two shear zones, where the gold mineralization is concentrated, the Sukari
granite is almost completely altered and transected by a large amount of quartz
veins.
Type of Deposit
& Mineralization
The vein-type deposit is hosted in Late Neoproterozoic granite that
intruded island-arc and ophiolite rock assemblages. The vein-forming process is
related to overall late Pan-African shear and extension tectonics. At Sukari,
bulk NE– SW strike-slip deformation was accommodated by a local flower
structure and extensional faults with veins that formed initially at conditions
of about 300 C and 1.5–2 kbar. Gold is associated with sulfides in quartz veins
and in alteration zones. Pyrite and arsenopyrite dominate the sulfide ore
beside minor sphalerite, chalcopyrite and galena. Gold occurs in three distinct
positions: (1) anhedral grains (GI) at the contact between As-rich zones within
the arsenian pyrite; (2) randomly distributed anhedral grains (GII) and along
cracks in arsenian pyrite and arsenopyrite, and (3) large gold grains (GIII)
interstitial to fine-grained pyrite and arsenopyrite.
Fluid inclusion studies yield minimum veinformation temperatures
and pressures between 96 and 188 _C, 210 and 1,890 bar, respectively, which is
in the range of epi- to mesothermal hydrothermal ore deposits. The structural
evolution of the area suggests a longterm, cyclic process of repeated veining
and leaching followed by sealing, initiated by the intrusion of granodiorite.
This cyclic process explains the mineralogical features and is responsible for
the predicted gold reserves of the Sukari deposits. A characteristic feature of
the Sukari gold mineralization is the co-precipitation of gold and arsenic in
pyrite and arsenopyrite.
