Can gold be found in a skarn?
Skarn deposits are economically valuable as sources of metals such as tin, tungsten, manganese, copper, gold, zinc, lead, nickel, molybdenum and iron. A skarn is formed by a variety of metasomatic processes during metamorphism between two adjacent lithologic units.
What is a skarn deposit?
Skarn-type deposits are formed in a similar process to 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 a mafic, ultramafic, felsic, or granitic intrusive body.
What is a gold skarn?
Gold skarns are defined as skarn deposits in which gold is the primary or dominant economic metal present. The following features should be noted about these deposits: 1. They occur worldwide along destructive plate margins (Figure 1) and tend to have a spatial and temporal association with Cu porphyry provinces.
What type of mineral deposit is gold?
Gold is found in two major types of deposits. Lode deposits are where gold is found in veins in rock. The second type is called a placer deposit that is formed by moving water that has eroded gold out of lode deposits.
What is the color of skarn?
Genetically, skarnoid is intermediate between a purely metamorphic hornfels and a purely metasomatic, coarse-grained skarn. Due to typical compositions of sedimentary protoliths it generally is pale in color and Fe poor in composition.
What Colour is skarn?
Skarn can form in almost any lithology type such as shale, granite and basalt but the majority of skarns are found in lithology containing a limestone or a dolomite. The attractive rock shown here is a rare variety of skarn dominated by bluish-colored diopside pyroxene (“violane” or “violan”) (Ca,Mg,Fe)₂Si₂O₆).
Where are gold deposits usually found?
Gold is usually found embedded in quartz veins, or placer stream gravel. It is mined in South Africa, the USA (Nevada, Alaska), Russia, Australia and Canada.
Is skarn a regional or contact?
Skarn, in geology, metamorphic zone developed in the contact area around igneous rock intrusions when carbonate sedimentary rocks are invaded by large amounts of silicon, aluminum, iron, and magnesium.
How can you tell if gold is quartz?
Try scratching a piece of glass with the gold. Real gold will not scratch a piece of glass, but other minerals that look like gold often do. If your piece of quartz has a corner or edge that looks like gold on it, try scratching this against a piece of glass. If it leaves a scratch, it is not real gold.
How are all types of skarn deposits formed?
The processes that lead to formation of all types of skarn deposits include: (1) isochemical contact metamorphism during pluton emplacement, (2) prograde metasomatic skarn formation as the pluton cools and an ore fluid develops, and (3) retrograde alteration of earlier-formed mineral assemblages.
Is it possible to find gold in a skarn?
In exploration, any skarn of any class should be routinely and systematically assayed for gold. Essentially, any calcareous or carbonate rock package intruded by an arc pluton has a potential for hosting Au skarn deposits, although such favorable packages are generally small and relatively rare in typical island arc or back-arc environments.
What kind of ore is found in Au skarns?
The gold in Au skarns is commonly micron -sized; thus, the ore is visually indistinguishable from waste. It may be associated with Bi-tellurides and arsenopyrite, and in some deposits there is an enrichment in Co.
Where are the skarn deposits in norther Mexico?
At Minera Bismark, a zinc-lead skarn deposit in norther n Mexico, water flows continuously along a major post-mineralization fault, as well as along other faults and fractures in granitic rock, necessitating a pumping system to dewater the orebody (Mining Magazine, 1994).