How is a porphyry copper deposit formed?
Porphyry copper deposits are copper ore bodies that are formed from hydrothermal fluids that originate from a voluminous magma chamber several kilometers below the deposit itself. Predating or associated with those fluids are vertical dikes of porphyritic intrusive rocks from which this deposit type derives its name.
What is porphyry copper systems?
Porphyry Cu systems are defined as large volumes (10->100 km3) of hydrothermally altered rock centered on porphyry Cu stocks that may also contain skarn, carbonate-replacement, sediment-hosted, and high- and intermediate-sulfidation epithermal base and precious metal mineralization.
How much of the earth’s Copper is found in porphyry copper deposits?
Porphyry mines produce more than 70% of global copper, nearly all of the molybdenum, and about 20% of the World’s gold—in addition, 80% of rhenium, nearly all tellurium, and significant silver and zinc are also produced as by-products (Sillitoe, 2010; John and Taylor, 2016).
How do VMS deposits form?
Over time, the continual activity of the smokers and their mineral rich plumes create mineralized beds that become VMS deposits. With the movement of the Earth’s tectonic plates, these mineral rich beds are transposed and can be found on land that was once underwater.
What is the meaning of porphyry deposit?
i. A deposit in which minerals of copper, molybdenum, gold, or less commonly tungsten and tin, are disseminated or occur in a stockwork of small veinlets within a large mass of hydrothermally altered igneous rock.
What is porphyry used for?
Porphyry is prized for its great compressive strength and exceptional durability. For this reason it is now most commonly used as a paving stone.
Where is porphyry found?
Porphyries are most commonly found along the west coast of North and South America, as well as in the Southwest Pacific. Porphyries are formed in tectonic plate convergent zones where oceanic crust has subducted beneath the continental crust, and in some cases the oceanic crust.
What is the difference between VMS and Sedex deposits?
VMS deposits are typically massive lens-shaped bodies, underlain by discordant vein mineralization and altered volcanic rocks. SEDEX deposits are finely layered massive sulfides interbedded with shale, siltstone, or sandstone, typical of deep marine turbidites.
What are VMS minerals?
A mineral is a naturally occurring inorganic element or compound having an orderly internal structure and characteristic chemical composition, crystal form, and physical properties. Common minerals include quartz, feldspar, mica, amphibole, olivine, and calcite.
What does porphyry look like?
The larger crystals are called phenocrysts. In its non-geologic, traditional use, the term porphyry refers to the purple-red form of this stone, valued for its appearance.
What is the color of porphyry?
purple
The term porphyry is from the Ancient Greek πορφύρα (porphyra), meaning “purple”. Purple was the color of royalty, and the “imperial porphyry” was a deep purple igneous rock with large crystals of plagioclase.
What is the difference between porphyry copper and sediment hosted copper?
In porphyry copper deposits, copper ore minerals are disseminated in igneous intrusions. Sediment-hosted stratabound copper deposits, in which copper is concentrated in layers in sedimentary rocks, account for about 20 percent of the world’s identified copper resources.
What is skarn deposit?
The “skarn”-type deposits are formed in a process similar to that of porphyry orebodies. Skarn deposits are developed due to replacement, alteration, and contact metasomatism of the surrounding country rocks by ore-bearing hydrothermal solution adjacent to mafic, ultramafic, felsic, or granitic-intrusive body.
What are the 5 criteria of a mineral?
What is a mineral?
- Minerals are naturally occurring. They are not made by humans.
- Minerals are inorganic. They have never been alive and are not made up from plants or animals.
- Minerals are solids.
- Minerals have a definite chemical composition.
- Minerals have an ordered atomic arrangement.