Sunday, January 10, 2010

Exodus 25:3 - A bit more about these specific metals

Before I move on to other parts of the Mishkan, I would like to take a deeper look into the properties of the metals used in construction:

Exodus 25:3
 And this is the offering which ye shall take of them; gold, and silver, and brass
‏וְזֹאת֙ הַתְּרוּמָ֔ה אֲשֶׁ֥ר תִּקְח֖וּ מֵאִתָּ֑ם זָהָ֥ב וָכֶ֖סֶף וּנְחֹֽשֶׁת

Top: Copper\Brass  - Silver - Gold
Bottom: Electrum

Lets turn to Wikipedia for some very basic facts about each one:

1) Gold

Gold is the most malleable and ductile of all metals; a single gram can be beaten into a sheet of 1 square meter, or an ounce into 300 square feet. Gold leaf can be beaten thin enough to become translucent. The transmitted light appears greenish blue, because gold strongly reflects yellow and red. Such semi-transparent sheets also strongly reflect infrared light, making them useful as infrared (radiant heat) shields in visors of heat-resistant suits, and in sun-visors for spacesuits.

Gold readily creates alloys with many other metals. These alloys can be produced to modify the hardness and other metallurgical properties, to control melting point or to create exotic colors. Gold is a good conductor of heat and electricity and reflects infrared radiation strongly. Chemically, it is unaffected by air, moisture and most corrosive reagents, and is therefore well-suited for use in coins and jewelry and as a protective coating on other, more reactive, metals.

In addition, gold is very dense, a cubic meter weighing 19300 kg. By comparison, the density of lead is 11340 kg/m3, and that of the densest element, osmium, is 22610 kg/m3.


Egyptian hieroglyphs from as early as 2600 BC describe gold, which king Tushratta of the Mitanni claimed was "more plentiful than dirt" in Egypt. Egypt and especially Nubia had the resources to make them major gold-producing areas for much of history. The earliest known map is known as the Turin Papyrus Map and shows the plan of a gold mine in Nubia together with indications of the local geology. The primitive working methods are described by Strabo and included fire-setting. Large mines also were present across the Red Sea in what is now Saudi Arabia.

General properties:

Name, symbol, number - gold, Au, 79
Element category - transition metal
Group, period, block - 11, 6, d
Standard atomic weight - 196.966569(4) g·mol−1
Electron configuration - [Xe] 4f14 5d10 6s1
Electrons per shell - 2, 8, 18, 32, 18, 1 (Image)

Physical properties:

Phase - solid
Density (near r.t.) - 19.30 g·cm−3
Liquid density at m.p. -17.31 g·cm−3
Melting point - 1337.33 K, 1064.18 °C, 1947.52 °F
Boiling point - 3129 K, 2856 °C, 5173 °F


2) Silver

Silver has been known since ancient times. Mentioned in the book of Genesis, slag heaps found in Asia Minor and on the islands of the Aegean Sea indicate that silver was being separated from lead as early as the 4th millennium BC using surface mining.
Silver is a very ductile and malleable (slightly harder than gold) monovalent coinage metal with a brilliant white metallic luster that can take a high degree of polish. It has the highest electrical conductivity of all metals, even higher than copper, but its greater cost and tendency to tarnish have prevented it from being widely used in place of copper for electrical purposes.


Among metals, pure silver has the highest thermal conductivity (the non-metal diamond and superfluid helium II are higher) and one of the highest optical reflectivity. (Aluminium slightly outdoes silver in parts of the visible spectrum, and silver is a poor reflector of ultraviolet light). Silver also has the lowest contact resistance of any metal.

Silver halides are photosensitive and are remarkable for their ability to record a latent image that can later be developed chemically.

Silver is stable in pure air and water, but tarnishes when it is exposed to air or water containing ozone or hydrogen sulfide to form a black layer of silver sulfide which can be cleaned off with dilute hydrochloric acid.
Many well known uses of silver involve its precious metal properties, including currency, decorative items and mirrors. The contrast between the appearance of its bright white color in contrast with other media makes it very useful to the visual arts. It has also long been used to confer high monetary value as objects (such as silver coins and investment bars) or make objects symbolic of high social or political rank.

Silver, in the form of electrum (a gold-silver alloy), was coined to produce money in around 700 BC by the Lydians. Later, silver was refined and coined in its pure form. Many nations used silver as the basic unit of monetary value.

Silver has been used for thousands of years for ornaments and utensils, for trade, and as the basis for many monetary systems. Its value as a precious metal was long considered second only to gold.



General properties:


Name, symbol, number - silver, Ag, 47
Element category - transition metal
Group, period, block - 11, 5, d
Standard atomic weight - 107.8682 g·mol−1
Electron configuration - [Kr] 4d10 5s1
Electrons per shell - 2, 8, 18, 18, 1 (Image)

Physical properties:
Phase - solid
Density (near r.t.) - 10.49 g·cm−3
Liquid density at m.p. - 9.320 g·cm−3
Melting point - 1234.93 K, 961.78 °C, 1763.2 °F
Boiling point - 2435 K, 2162 °C, 3924 °F


3) Copper\Brass

Copper has a reddish, orangish, or brownish color because a thin layer of tarnish (including oxides) gradually forms on its surface when gases (especially oxygen) in the air react with it. But pure copper, when fresh, is actually a pinkish or peachy metal. Copper, caesium and gold are the only three elemental metals with a natural color other than gray or silver.

In its liquefied state, a pure copper surface without ambient light appears somewhat greenish, a characteristic shared with gold. When liquid copper is in bright ambient light, it retains some of its pinkish luster. When copper is burnt in oxygen it gives off a black oxide.


Copper is easily worked, being both ductile and malleable. The ease with which it can be drawn into wire makes it useful for electrical work in addition to its excellent electrical properties. Copper can be machined, although it is usually necessary to use an alloy for intricate parts, such as threaded components, to get really good machinability characteristics. Good thermal conduction makes it useful for heatsinks and in heat exchangers. Copper has good corrosion resistance, but not as good as gold. It has excellent brazing and soldering properties and can also be welded, although best results are obtained with gas metal arc welding
At 59.6 × 106 S/m copper has the second highest electrical conductivity of any element, just after silver.

Copper is germicidal, via the oligodynamic effect. For example, brass doorknobs disinfect themselves of many bacteria within a period of eight hours. Antimicrobial properties of copper are effective against MRSA, Escherichia coli,and other pathogens. In colder temperature, longer time is required to kill bacteria.

Copper has the intrinsic ability to kill a variety of potentially harmful pathogens. Frequently touched surfaces in hospitals and public facilities harbor bacteria and increase the risk for contracting infections. Covering touch surfaces with copper alloys can help reduce microbial contamination associated with hospital-acquired infections on these surfaces.

Brass is any alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties

Brass has a muted yellow color, somewhat similar to gold. It is relatively resistant to tarnishing, and is often used as decoration and for coins. In antiquity, polished brass was often used as a mirror.

Alloying of copper with zinc or tin to make brass or bronze was practiced soon after the discovery of copper itself. There exist copper and bronze artifacts from Sumerian cities that date to 3000 BC,  and Egyptian artifacts of copper and copper-tin alloys nearly as old. In one pyramid, a copper plumbing system was found that is 5000 years old. The Egyptians found that adding a small amount of tin made the metal easier to cast, so copper-tin (bronze) alloys were found in Egypt almost as soon as copper was found. Very important sources of copper in the Levant were located in Timna valley (Negev, now in southern Israel) and Faynan (biblical Punon, Jordan).

General properties:


Name, symbol, number - copper, Cu, 29
Element category - transition metal
Group, period, block - 11, 4, d
Standard atomic weight - 63.546(3) g·mol−1
Electron configuration - [Ar] 3d10 4s1
Electrons per shell - 2, 8, 18, 1 (Image)

Physical properties:

Phase - solid
Density (near r.t.) - 8.94 g·cm−3
Liquid density at m.p. - 8.02 g·cm−3
Melting point - 1357.77 K, 1084.62 °C, 1984.32 °F
Boiling point - 2835 K, 2562 °C, 4643 °F



4) Electrum

Electrum is a naturally occurring alloy of gold and silver, with trace amounts of copper and other metals. It has also been produced artificially. The ancient Greeks called it 'gold' or 'white gold', as opposed to 'refined gold'. Its color ranges from pale to bright yellow, depending on the proportions of gold and silver. The gold content of naturally occurring electrum in modern Western Anatolia ranges from 70% to 90%, in contrast to the 45–55% of electrum used in ancient Lydian coinage of the same geographical area. This suggests that one reason for the invention of coinage in that area was to increase the profits from seignorage by issuing currency with a lower gold content than the commonly circulating metal.


Electrum was used as early as the third millennium BC in Old Kingdom Egypt, sometimes as an exterior coating to the pyramidions atop ancient Egyptian pyramids and obelisks.

Electrum was also used in the making of ancient drinking vessels and coins.

The color of electrum is pale yellow or yellowish-white and the name is a Latinized form of the Greek word ἤλεκτρον (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.

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