Minerals containing high grade silver appear as dark and light gray portions (crystals) in these ore specimens from the northern part of the Comstock Lode Mining District in Virginia City, Nevada, USA.
STEPHANITE is often so black that it seems to absorb all light and in other conditions it has a dark blue cast.
The ARGENTITE mineral is often a light to medium gray in translucent rock material such as quartz.
Stephanite and Argentite are minerals of silver as noted in the store and museum placards.
ELECTRUM is a natural alloy of gold and silver having colorations of yellowish-orange to golden to golden-brownish in translucent material such as quartz. High grade, relative to ancient times, electrum was used by the Roman Empire to make their coinage.
NATIVE GOLD, visible gold not chemically combined with other elements, can be seen as chunks, streaks, veining, clusters of specs and/or dotted with grains in these series of high grade precious metal ore samples of Au and Ag.
NATIVE SILVER is found in one specimen in this series.
(Au): the Atomic symbol for Gold from the Latin word "Auriferous".
au·rif·er·ous (ô-rif-er-ous) adj. Containing gold; gold-bearing. [From Latin aurifer, gold-bearing : aurum, gold + -fer, -fer.]
AURIFEROUS: adjective (Earth Sciences / Geological Science) (of rock) containing gold; gold-bearing
[from Latin aurifer gold-bearing, from aurum gold + ferre to bear]
From Latin aurifer (“‘gold-bearing’”) + the English suffix -ous. The Latin term in turn derived from aurum (“‘gold’”) + fero (“‘I carry’”).
(Ag): the Atomic Element symbol for Silver from the Latin word "Argentum", from the Indo-European root *arg- for "white" or "shining")
ARGENTIFEROUS: ar·gen·tif·er·ous adjective - Bearing or producing silver.
Au & Ag, Latin abbreviations, are used in the scientific Chemical Periodic Chart of 92 naturally occuring Elements
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the mineral cubic silver sulfide (Ag2S) with a blackish lead-grey color and metallic lustre.
The mineral is perfectly sectile and has a shining streak. It occurs in mineral veins, and when found in large masses, as in is Mexico & in the Comstock Lode in Nevada, an important ore of silver.
(from the Lat. argentum, silver)
Electrum, is a naturally comprised alloy of Gold & Silver which at times could contain Gold as high as 90% but could also be as low as 40% resulting in a pale color due to its high Silver content. This natural hybrid was plentiful in the sands of the Pactolus river located on the Western outskirts of the Lydian capitol, Sardes.
Electrum, circulated in western Asia minor during the reigns of Gyges, Ardys, Sadyattes & Alyattes (685 - 561 BCE) but this would all change during the reign of the legendary Lydian king Croesus (561 - 546 BCE) who outlawed the use of Electrum after his successful achievement of Gold refining and whose coinage will soon be discussed.
Electrum is a naturally occurring alloy of gold & silver, with trace amounts of copper and other metals. Its color ranges from pale to bright yellow, depending on the proportions of gold and silver.
Electrum consists primarily of gold and silver, electrum is a good conductor of electricity.
The color of electrum is pale yellow or yellowish-white and the name is a Latinized form of the Greek word (elektron) mentioned in the Odyssey meaning a metallic substance consisting of gold alloyed with silver. The same word was also used for the substance amber, probably because of the pale yellow color of certain varieties, and it is from the electrostatic properties of amber that the modern English words "electron" and "electricity" derive. Electrum was often referred to as white gold in ancient times but could be more accurately described as "pale gold". The modern use of the term white gold usually concerns gold alloyed with any one or a combination of nickel, silver, platinum and palladium to produce a silver-colored gold.
Electrum was much better for coinage than gold, mostly because it was harder and more durable.
Stephanite is a silver antimony sulfide mineral with formula: Ag5SbS4...containing 68.8% silver.
Under the name Schwarzerz .."black silver ore" (German Schwarzgultigerz) ["Schwarz" = "Black"].
Stephanite crystals have the form of six-sided prisms or flat tables terminated by large basal planes and often modified at the edges by numerous pyramid-planes. The color is iron-black, and the luster metallic and brilliant.
Stephanite occurs with other ores of silver in metalliferous veins. In the Comstock lode in Nevada massive stephanite and argentite are important ores of silver.
Silver is a chemical element with the chemical symbol Ag (Latin: argentum, from the Ancient Greek: argeentos, gen. of - argeeis, "white, shining" ) and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal. The metal occurs naturally in its pure, free form (native silver), as an alloy with gold (electrum) and other metals, and in minerals such as argentite and chlorargyrite. Most silver is produced as a by-product of copper, gold, lead, and zinc refining.
An ore is a type of rock that contains minerals such as gemstones or metals that can be extracted through mining and refined for use. Samples of ore in the form of exceptionally beautiful crystals, exotic layering visible when sectioned or polished or metallic presentations such as large nuggets or crystalline formations of metals such as gold or copper may command a value far beyond their value as mere ore or raw metal for subsequent reduction to utilitarian purposes.
The grade or concentration of an ore mineral, or metal, as well as its form of occurrence, will directly affect the costs associated with mining the ore. The cost of extraction must thus be weighted against the contained metal value of the rock to determine what ore can be profitably extracted and what ore is of too low a grade to be worth mining. http://en.wikipedia.org/wiki/Ore
["Cut-Off Grade": the break-even value per unit such as Ounces Per Ton (OPT) or Grams Per Ton (g/tn). Mining company extraction system does not try to obtain gold below their stated "cut-off grade" (percentage of precious metal per ton of ore). 0.03 OPT-Au (1 g/tn) is a common cut-off grade for a sophisticated mining operation. Substantial mining companies and/or in countries with low expenses of labor can profit with cut-off grades as low as 1/2 to 1/3 gram per ton for gold (.015 to .010 OPT-Au [1/100th of an ounce from a ton of rock or dirt about the size of wooden pallet two to three feet high or as much as half the bed of a small pick-up truck] - such mining is with "disseminated" mineral deposits, since the gold is often very fine it has been nick named "flour gold" and may be even distributed so sparsely in a volume of ore that it can only be detected by microscope and/or chemical analysis - such is the main deposition source in the northern Nevada precious metal mineralization belts from east to west:
1. Carlin Trend
2. Battle Mountain Trend
3. Round Mountain Trend
Some of the sparse and fine deposits were from saltwater deposition when much of Nevada in pre-historic times was covered by an inland sea.
It is amazing what Modern Mining has discovered and process at a profit!]
MILKY QUARTZ is the second most abundant mineral in the Earth's continental crust after feldspar. Quartz is made up of a continuous framework of SiO4 silicon-oxygen [silica] tetrahedra, each oxygen being shared between two tetrahedra, giving an overall formula SiO2.
[Other documents cite the "silica" molecule (SiO4) as the most abundant mineral in the Earth.
TETRAHEDRON is a 4-sided pyramid, a 3-D triangle with the base plane as the 4th face ("tetra" = "four" + "hedron" = "face/a planar side" of a 3-D form. "Hedra" is the plural form.) An atom of the element Silicon (Si) is in the the centroid of the pyramid, electro-magnetically connecting to four oxygen atoms by electron sharing. Oxygen (O) is the atom at each of the four corners (nodes) of the electro-magnetic pyramid. Silica Pyramids connect by sharing an oxygen node in a third-dimensional array known as a lattice also known as a "crystalline structure", a strong form of chemical bonding, hence quartz has substantial hardness.]