Minerals/Metals/Precious
![](http://upload.wikimedia.org/wikipedia/commons/thumb/f/ff/Gold-cat12a.jpg/250px-Gold-cat12a.jpg)
Precious metals are usually rare, chemically relatively inert, and often colorful.
They are transition metals ruthenium (Ru) through silver (Ag) and rhenium (Re) through gold (Au).
Golds
[edit | edit source]![](http://upload.wikimedia.org/wikipedia/commons/thumb/f/f1/Gold_nugget_%28placer_gold%29_2_%2817025829922%29.jpg/250px-Gold_nugget_%28placer_gold%29_2_%2817025829922%29.jpg)
Gold (Au) is the most prestigious metal known, but it's not the most valuable. Gold is the only metal that has a deep, rich, metallic yellow color. Almost all other metals are silvery-colored. Gold is very rare in crustal rocks - it averages about 5 ppb (parts per billion). Where gold has been concentrated, it occurs as wires, dendritic crystals, twisted sheets, octahedral crystals, and variably-shaped nuggets. It most commonly occurs in hydrothermal quartz veins, disseminated in some contact- & hydrothermal-metamorphic rocks, and in placer deposits. Placers are concentrations of heavy minerals in stream gravels or in cracks on bedrock-floored streams. Gold has a high specific gravity (about 19), so it easily accumulates in placer deposits. Its high density allows prospectors to readily collect placer gold by panning.
Platinums
[edit | edit source]![](http://upload.wikimedia.org/wikipedia/commons/thumb/6/6a/Platinum-nugget.jpg/250px-Platinum-nugget.jpg)
Platinum can also occur as nuggets such as the one imaged on the right from Russia.
Silvers
[edit | edit source]![](http://upload.wikimedia.org/wikipedia/commons/thumb/b/b1/Silver-280342.jpg/250px-Silver-280342.jpg)
![](http://upload.wikimedia.org/wikipedia/commons/thumb/7/7c/Native_silver.jpg/250px-Native_silver.jpg)
Native silver does occur as cubic, octahedral, or dodecahedral crystals; "also elongated, arborescent, reticulated, or as thin to thick wires."[1]
Iridiums
[edit | edit source]![](http://upload.wikimedia.org/wikiversity/en/1/1c/Cubic_native_iridium_crystal.png)
Native iridium such as the small cubic crystal shown in the image on the right is rare.
Osmiums
[edit | edit source]![](http://upload.wikimedia.org/wikiversity/en/b/b1/Native_Osmium_crystal.png)
The crystal of native osmium shown on the right is about 2 mm across.
Palladiums
[edit | edit source]![](http://upload.wikimedia.org/wikiversity/en/1/1d/Palladium_nugget_Brazil.png)
![](http://upload.wikimedia.org/wikiversity/en/thumb/3/35/Palladium_Mednorudyanskoye_Cu_Deposit.jpg/250px-Palladium_Mednorudyanskoye_Cu_Deposit.jpg)
"Natural Palladium [like the nugget shown on the right] always contains some Platinum."[2]
This palladium nugget is from Bom Sucesso Creek, Serro, Minas Gerais, Brazil.
"(Pd,Cu) alloys, some with the approximate composition PdCu4, are reported by Kapsiotis et al. (2010)."[2]
The piece of native palladium [image on the left] from the Mednorudyanskoye Cu Deposit, Nizhnii Tagil, Sverdlovskaya Oblast', Middle Urals, Urals Region, Russia, probably contains some copper.
Potarites
[edit | edit source]![](http://upload.wikimedia.org/wikiversity/en/thumb/d/d7/Potarite_from_Brazil.jpg/250px-Potarite_from_Brazil.jpg)
Potarite has the chemical formula PdHg.[1]
On the right is a piece of potarite is from Serro, Minas Gerais, Brazil.
Rheniums
[edit | edit source]![](http://upload.wikimedia.org/wikiversity/en/7/7a/Native_rhenium_2.png)
"Native rhenium was first discovered in the Earth's crust in wolframites from a rare metal deposit in the Transbaikal region [1]. [...] The study of the lunar regolith from two sites revealed native rhenium particles with different morphological features: irregular dense particles from Mare Fecunditatis and spheroidal particles from Mare Crisium. The origin of particles (less than 10 µm in size) is assigned to exhalative processes [2]. Among the extraterrestrial objects, native rhenium was found in Ni-iron and silicates from the Allende meteorite [3]."[3]
Rhodiums
[edit | edit source]![](http://upload.wikimedia.org/wikiversity/en/thumb/c/c5/Native_rhodium.jpg/250px-Native_rhodium.jpg)
The image on the right contains small particles of native rhodium-bearing ferroplatinum. This sample was obtained from the lunar regolith "by the Luna-16 automatic station".[4]
"Terrestrial iron-free rhodium-bearing platinum with the composition of Pt0.68Rh0.32 in association with platinum-bearing rhodium Rh0.57Pt0.43 [...] was originally discovered in heavy fractions from basic rocks (norite, gabbro, and anorthosite) in the upper zone of the layered Stillwater intrusion (Montana, United States) [2]."[4]
Rutheniums
[edit | edit source]![](http://upload.wikimedia.org/wikiversity/en/c/c1/Native_Ruthenium_from_Verkneivinsk.png)
The piece of native ruthenium in the image on the right contains some iridium. It is from Verkhneivinsk, Neiva river, Sverdlovskaya Oblast', Middle Urals, Urals Region, Russia.
Hypotheses
[edit | edit source]- Precious metals have variable value so may only be used as an interim investment.
See also
[edit | edit source]References
[edit | edit source]- ↑ 1.0 1.1 Willard Lincoln Roberts; George Robert Rapp Jr.; Julius Weber (1974). Encyclopedia of Minerals. New York, New York, USA: Van Nostrand Reinhold Company. pp. 121-2. ISBN 0-442-26820-3.
- ↑ 2.0 2.1 Hudson Institute of Mineralogy (29 October 2015). Palladium. Mindat. http://www.mindat.org/min-3067.html. Retrieved 2015-11-04.
- ↑ A. F. Grachev; S. E. Borisovsky; A. V. Grigor’eva (October 2008). "The first find of native rhenium in the transitional clay layer at the Cretaceous/Paleogene boundary in the Gams Section (eastern Alps, Austria)". Doklady Earth Sciences 422 (1): 1065-7. doi:10.1134/S1028334X08070131. http://link.springer.com/article/10.1134/S1028334X08070131. Retrieved 2015-11-04.
- ↑ 4.0 4.1 T. A. Gornostaeva; P. M. Kartashov; A. V. Mokhov; O. A. Bogatikov (2012). "Native Rhodium-Bearing Ferroplatinum in a Lunar Regolith Sample from the Mare Fecunditatis". Doklady Earth Sciences 444 (2): 770-2. doi:10.1134/S1028334X12060220. http://link.springer.com/article/10.1134/S1028334X12060220#/page-1. Retrieved 2015-11-04.