How it may have been
Gold mining is the process of locating and extracting gold or gold ores from the ground. There are several techniques and processes by which gold may be extracted from the earth.
Gold mining in Nevada is a major industry, and one of the largest sources of gold in the world. Nevada currently mines 79% of all the gold in the United States, worth over US $228 billion.
Gold is actually a relatively scarce element on the crust of the earth, but it occurs in trace quantities spread throughout many different kinds of rocks and in many different geological environments. Although scarce, gold is concentrated by various natural geologic processes to form commercial deposits of two principal types: hard rock lode (primary) deposits and placer (secondary) deposits.
Hard rock deposits are the gold deposits locked in solid rock formations. These are the targets for the "hardrock" prospector seeking gold at the site of its deposition which was formed from mineralizing solutions within the earth. These deposits within solid rock are also the source of most of the new gold being mined today. Gold is most commonly deposited in areas open to circulation of hot liquids such as fracture zones along faults. This explains why veins of gold are so closely related to fault activity. Gold is usually only a small portion of the deposit, and associated minerals such as quartz, calcite, pyrite are discarded even though they may contain trace gold..
Placer Deposits are the natural concentrations caused by the effect of gravity on moving particles. When heavy, stable minerals are freed from their matrix (hard rock) by weathering processes, they are slowly washed downslope into streams that quickly winnow the lighter matrix. Thus the heavy minerals become concentrated in stream, beach, and residual gravels and constitute workable ore deposits. This is the gold which is 'panned' (or commercially dredged).
Geologic Setting. Golden Arrow is situated along the western margin of the Kawich volcanic caldera, a zone of complicated geological formations including complex faulting, igneous intrusion, volcanism, and hydrothermal mineralization resulting from the North American continent colliding with the Pacific tectonic plate. This has created the formation of a great variety of gold, silver and other mineral deposits. The area has past production and defined resources of more than 30 million ounces of gold and 400 million ounces of silver.
History. High-grade gold-quartz veins were discovered at Golden Arrow in 1905 and mined through the 1930’s from numerous shafts to 500 foot depth, where the mines watered out and were abandoned. Efforts were renewed in the 1960's but by the 1980's the mines of Golden Arrow were abandoned for good.
____________________________________________________________________
There are different types of mine waste materials which vary in their composition, their potential for environmental contamination, and how they are managed at mine sites. Types of mine waste include:
Overburden: Overburden includes the soil and rock that is removed to gain access to the ore deposits at mines. It is usually piled on the surface at mine sites where it will not impede further expansion of the mining operation. Overburden generally has a low potential for environmental contamination, and is often used at mine sites for landscape contouring and revegetation during mine closure.
Waste rock: Waste rock is material that contains minerals in concentrations considered too low to be extracted at a profit. Waste rock is often stored in heaps or dumps on the mine site.
Tailings: Tailings are finely ground rock and mineral waste products of mineral processing operations. Tailings are usually deposited in the form of a water-based slurry into tailings ponds (sedimentation lagoons enclosed by dams built to capture and store the tailings).
Slags: Slags are non-metallic by-products from metal smelting, and were historically considered to be waste. Slags are largely environmentally benign, and are being used increasingly as aggregate in concrete and road construction.
Mine water: Mine water is produced in a number of ways at mine sites, but the only water here is far underground where shaft met spring and flooded.
____________________________________________________________________
Deposit Styles and Gold Mineralization
Did you know? Unlike coal and oil extraction, where mining companies pay royalties for minerals obtained from public lands, gold mining companies do not pay any royalties for deposits claimed on federal public lands. This is because gold mines on public land (like Golden Arrow) operate under the General Mining Act of 1872.
A, B, C
D, E, F
The posted coordinates will bring you to the ghostly remains of the Golden Arrow mine. DANGER! Do not approach the mine workings! KEEP OUT! DANGER!
To earn credit for this earthcache and to demonstrate the educational value of your visit, please email these answers to me via my profile page:
1. What are the two principal gold deposit types?
2. Which type of deposit was being mined here?
3. What caused the mines to be abandoned?
4. What minerals described herein were discarded by the mining process?
5. After studying the mineral, did you see any flecks of Gold?
6. Which of the images in the six-block above represents the mine workings located here?
Do not post answers in your log. And no pics here, please. As always, logs not followed by answers within 48 hours will be deleted. You can always log again when prepared.
DO NOT POST IMAGES OF THIS LOCATION PLEASE
The ET Earthcache series include the most FAVORITED Earthcaches in Nevada! Thanks to everyone who posts a
FAVORITE
_____________________________
Alamo to Tonopah Earthcaches:
Groom Mining District Rachel, NV (GC2GHE8)
Alamo Breccia Alamo, NV (GC37ZKW)
Playa Goblin Knobs, NV (GC2GP44)
Walker Lane Tonopah, NV (GC36DRD)
Golden Arrow Mine Golden Arrow, NV (GC4QX9J)
__________________________