Atomic Number ........................................ 47
Atomic Weight ........................................ 107.88
Density (g/cm^3) ..................................... 10.49
Density (lb/in^3) .................................... 0.3787
Melting Point (C) .................................... 960.80
Melting Point (F) .................................... 1761.44
Boiling Point (C) .................................... 2210
Boiling Point (F) .................................... 4010
Specific Heat (cal/g-C) .............................. 0.0559
Specific Heat (J/kg-K) ............................... 234
Heat of Fusion (cal/g) ............................... 25
Heat of Fusion (Btu/lb) .............................. 45
Coefficient of linear thermal expansion (uin/in/C) ... 19.68
Coefficient of linear thermal expansion (uin/in/F) ... 10.9
Thermal conductivity (cal/cm^2/cm/sec/C) ............. 1.0
Electrical resistivity (uohm-cm) ..................... 1.59
Modulus of elasticity in tension (psi) ............... 11

Formula               DH0f       DG0f       S0         C0p
                      kJ/mol     kJ/mol     J/K mol    J/K mol
Ag(c)                   0.0        0.0        42.55      25.351
Ag(g)                 284.55     245.65      172.997     20.786
Ag+(g)               1021.73     --           --           --
Ag2CO3(c)            -505.8     -436.8       167.4      112.26
Ag2O(c)               -31.05     -11.20      121.3       65.86
Ag2S(c,argentite)     -32.59     -40.67      144.01      76.53
AgCN(c)               146.0      156.9       107.19      66.73
AgCNS(c)               87.9      101.39      131.0       63.
AgCl(c,cerargyrite)  -127.068   -109.789      96.2       50.79
AgBr(c)              -100.37     -96.90      107.1       52.38
AgI(c)                -61.83     -66.19      115.5       56.82
AgNO3(c)             -124.39     -33.47      140.92      93.05
Ag3PO4(c)                --     -879.           --         --
Ag2CrO4(c)           -731.74    -641.76      217.6      142.26
Ag2SO4(c)            -715.88    -618.41      200.4      131.38

----------------------------------------------------------------------------
Notes: These molar values apply to pure substances at 25oC and exactly
100000 Pa (1.0 bar or 100 kPa) pressure. One standard atmosphere pressure is
slightly higher, 101325 Pa, but the change in tabulated values between these
two pressures is neglegible for all solids and liquids and minor even for
gases. Physical states are indicated by c (crystalline solid), l (liquid),
and g (gas). Different crystalline structures are designated by common or
mineralogical names. Common names for selected compounds are also given.
Values are taken from U.S.N.B.S. tables of molar thermodynamic properties
(J. Phys. Chem. Ref. Data 11, Suppl. 2 (1982)) unless in italics.
----------------------------------------------------------------------------

Formula          DH0f       DG0f       S0       C0p
                 kJ/mol     kJ/mol     J/K mol  J/K mol
Ag+             105.579     77.107    72.68    21.8
AgCl2-         -245.2     -215.4     231.4       -
Ag(NH3)2+      -111.29     -17.12    245.2       -
Ag(S2O3)23-       --     -1285.7       --        -

----------------------------------------------------------------------------
Notes: These standard molar values apply to (infinitely) dilute aqueous
solutes at 25oC and exactly 100 kPa (1.0 bar) pressure. One standard
atmosphere pressure is slightly higher, 101.325 kPa, but the change in
tabulated values between these two pressures is neglegible for all solids,
liquids, and ions. It is minor even for gases. Values are taken from
U.S.N.B.S. tables of molar thermodynamic properties (J. Phys. Chem. Ref.
Data 11, Suppl. 2 (1982)) unless in italics.
----------------------------------------------------------------------------

Compound   Ksp            
AgBr       5.35 x 10-13 
Ag2CO3     8.45 x 10-12   
AgCl       1.76 x 10-10
Ag2CrO4    1.12 x 10-12 
AgCN       5.97 x 10-17 
AgI        1.18 x 10-16 
Ag3PO4     8.88 x 10-17 
Ag2SO4     1.20 x 10-5  
Ag2S       6.69 x 10-50 
AgCNS      1.03 x 10-12 

----------------------------------------------------------------------------
Notes: These molar values apply in (infinitely) dilute aqueous solutions at
25øC. The values are calculated from U.S.N.B.S. tables of molar
thermodynamic properties unless in italics. Solubility products are the
equilibrium constants for the formation of solutions of the constituent ions
of a slightly soluble salt from the pure solid salt.
----------------------------------------------------------------------------

Ion            Constant     log Kstab  

Ag(CN)2-       2.47 x 10+20   20.394   
Ag(NH3)2+      1.67 x 10+7     7.223   
AgCl21-        1.38 x 10+5     5.140   

----------------------------------------------------------------------------
Notes: These molar values apply in (infinitely) dilute aqueous solutions at
25oC. The values are calculated from U.S.N.B.S. tables of molar
thermodynamic properties unless in italics. Stability constants are the
equilibrium constants for the formation of the complex ion from its
constituent simpler ions.
----------------------------------------------------------------------------

Electrode Couple          E0, V     dE0/dT, mV/K
AgCl + e- --> Ag + Cl-    +0.2221   -0.648
Ag+ + e- --> Ag           +0.7991   -0.989

----------------------------------------------------------------------------
Notes: Values for 0.1 MPa and 25oC in aqueous 1.0 molar acid solution,
calculated from U.S.N.B.S. tables of molar thermodynamic properties unless
in italics. The potential values are given to the nearest 0.1 mV if known,
thermal coefficients to the nearest 0.001 mV/K if known. The thermal
coefficient is that of the isothermal cell in which one of the electrodes is
the standard hydrogen electrode. Ions are all aqueous. Elements and
compounds are pure substances, present in their usual state at 25oC, unless
otherwise indicated. The saturated calomel reference potential is the
experimental value for pure mercury in contact with an aqueous solution
saturated with both Hg2Cl2 and KCl.
----------------------------------------------------------------------------

Introduction

Silver's (Ag) relative scarcity, attractive appearance and malleability (for easy shaping) have made it suitable for use in jewellery, ornaments and silverware since before ancient Roman times. Its use has been extensive in coins throughout history but has declined in recent times. In Australia, the 1966 fifty cent piece was the last coin in general use to contain silver (80% silver, 20% copper). Although silver is resistant to oxidation, it readily forms a surface tarnish of silver sulphide. While its high electrical and thermal conductivity make it useful in the electronics industry, the largest use of silver is in photographic paper and film.

Silver is mined and produced mainly as a co-product of copper, lead, zinc, and to a lesser extent, gold. Its main source is silver minerals in lead ore.

Occurrence

The main silver minerals are tetrahedrite (Cu,Fe,Zn,Ag)12Sb4S13, freibergite (tetrahedrite with up to 30% Ag), pyragyrite (Ag3SbS3), argentite (Ag2S), proustite (Ag3AsS3), ceragyrite (AgCl). Australian silver mainly occurs as trace amounts of freibergite, tetrahedrite and pyragyrite in the lead mineral galena (PbS). Silver in gold ores occurs mainly as minor amounts of the natural gold-silver alloy called electrum.

Warm to hot (hydrothermal) fluids generated within the earth form copper, lead and zinc deposits, which contain silver. These fluids may be trapped below the surface in cracks where galena, with trace silver, and other minerals precipitate to make vein deposits. Where limestones occur the fluids fill cavities to form rich but patchy lead-zinc-silver deposits. Some fluids can reach the ocean floor, in areas of underwater volcanic activity, to form 'volcanogenic' deposits.

Partially eroded deposits exposed at the surface were relatively easily discovered. Examples are the Broken Hill deposit in New South Wales and the Mt Isa deposit in Queensland.

These deposits formed the basis of Australia's silver (lead-zinc) mining industry.

Exposed deposits are becoming harder to find in Australia, and exploration companies are now looking beneath the surface for the deposits of the future. This is a more costly and difficult way to find orebodies, but a series of successes have occurred since the late 1970s. Such discoveries include the Scuddles mine in Western Australia (140 metres deep), the Cannington deposit in north Queensland (10 metres deep), the Hellyer mine in Tasmania (90 metres deep), and the Wilga-Currawong mine in Victoria (50 metres below the surface).

Australian Resources and Deposits

In 1883, Charles Rasp discovered the Broken Hill deposit when he found some dark, heavy rocks which he thought may contain tin. Subsequent assays (analysis) of these rocks proved that he had located rich oxidised (weathered) silver and lead minerals.

The upper parts of the Broken Hill deposit (and Mt Isa) were very rich in silver- the prime commodity sought in the early days. The wealth generated by mining the Broken Hill ore allowed The Broken Hill Proprietary Company Limited to prosper and, although it no longer has an interest in the deposit, BHP Ltd has become Australia's largest company.

Over a hundred years after discovery, silver (lead, zinc) mining continues at Broken Hill.

John Campbell Miles discovered rich lead-silver lodes at Mt Isa in 1923 where production continues even after 70 years of mining. Mt Isa now outstrips Broken Hill as the largest producer in Australia. Discovery of the nearby rich Hilton deposit occurred in the late 1940s but it was not developed until the mid 1950s. Cannington (very rich), Century and Dugald River are other large deposits yet to be mined in the region. In the Northern Territory, the huge McArthur River lead-zinc-silver deposit is being developed.

The Olympic Dam copper deposit in South Australia, contains large resources of silver which are produced as a by-product of copper refining. Silver is produced as a co-product of lead-zinc(copper) mining at Rosebery and Hellyer in Tasmania; Elura, Woodlawn and Cobar in New South Wales; Woodcutters in the Northern Territory; Cadjebut and Scuddles in Western Australia; Wilga-Currawong in Victoria and Thalanga in Queensland. Most gold mines throughout Australia also produce silver.

Australia in the World

Australia, along with the former USSR, Canada, Mexico and the USA, has a major share of the world's economic silver resources.

Australia's silver production ranks after Mexico, USA, Peru and Canada but the development of the McArthur River deposit will increase Australia's output. About 30% of Australia's mine output is refined to silver metal with most of the remainder exported to the United Kingdom in lead bullion, where it is extracted and refined.

Mining and Processing

Most of Australia's silver is produced from the silver-bearing lead mineral, called galena. Some is also produced from copper and gold mining.

Almost all of Australia's silver (lead-zinc and/or copper) mines are highly mechanised, underground operations. Ore is drilled and blasted in large volumes and transferred to underground rock crushers by large loaders and trucks. The crushed ore is then hoisted to the surface in skips or driven directly to the surface by truck via a spiral access (decline). A continuous underground mining machine is currently being developed at Broken Hill to increase efficiency by replacing the drill and blast phase.

At the surface, the ore is subjected to additional crushing and fine grinding. A flotation process is used to separate the silver-bearing galena from the waste rock particles (tailings) to form a concentrate. Development of the flotation process occurred in the early days of mining at Broken Hill. Today, more efficient versions of this technology are used world-wide. Many mines around Australia and overseas use the improved Jameson flotation cell, also developed in Australia.

Ground-up ore, water and special chemicals are mixed together and constantly agitated in banks of flotation cells. Air is blown through the mixture in each cell and fine silver bearing galena particles stick to the bubbles, which rise to form a froth on the surface of the cell. The tailings sink to the bottom of the cell and are removed. The froth is skimmed off and the resulting silver-lead sulphide concentrate may assay 800 grams to 1 kilogram of silver per tonne of concentrate.

The concentrate is sintered (heated but not melted) to combine the fine particles into lumps and to remove the sulphur as sulphur dioxide. It is then smelted in a blast furnace and drossed (removal of trace copper and impurities) to produce crude lead metal that may contain over 2 kilogram of silver per tonne of concentrate.

Silver is recovered when crude lead is refined to high purity. Crude lead is reheated or re-melted and antimony and other impurities removed. The molten lead is then poured into a large upright container called a 'kettle' where it plunges through a molten zinc metal layer floating on top of molten lead. The kettle is increasingly cooled towards its base so that as the incoming molten lead descends, the contained silver (and any minor gold or copper) combines with the molten zinc to form crystals of zinc-silver-gold-copper alloy which float to the surface and re-dissolve in the zinc layer, which is periodically skimmed off. The remaining silver-gold-copper alloy (called dore) is cast into plates for later electrolytic removal of copper and separation of high purity silver and gold.

The Port Pirie lead smelter and refinery in South Australia is the most important Australian producer of refined silver, with most of the lead concentrates processed from the Broken Hill mine. Most of the silver output from Mt Isa and Hilton mines is in lead concentrates which are smelted to lead bullion at Mt Isa. The bullion is exported to the United Kingdom for refining and silver extraction. Lead bullion, containing silver, is produced at the Cockle Creek smelter (NSW) from Broken Hill, Woodlawn and Cobar mine concentrates. The bullion is sent to Port Pirie or exported for refining and extraction of silver.

Silver is also produced at the Port Kembla copper refinery in NSW from silver and gold rich residues formed during electrolytic refining of crude copper metal (produced from Cobar and Woodlawn mines concentrates) and from silver-gold residues from the Townsville copper refinery. The process involves smelting the residues, and added jewellery scrap, to produce a silver-gold dore (bullion). The gold is then separated electrolytically and the resulting silver is melted into high purity ingots. Silver ingots are also produced at the Olympic Dam mine from residues generated during electrolytic copper refining.

Silver is extracted and refined from gold dore (bullion), sourced mainly from Australian gold mines, by gold refineries in Perth, Kalgoorlie and Melbourne.

Uses

The use of silver dates from the earliest historic records and it was usually extracted by melting lead ore (galena). Silver ornaments and utensils have been used since the 4th century BC. The Romans produced silver from lead-silver mines, smelters and refineries in Britain, Sardinia, Spain and elsewhere and it became the basis of their coinage. In the 16th and 17th centuries, Spain explored and colonised South America and, as a result, mining from rich deposits discovered in Mexico, Peru and Bolivia caused a large increase in world silver production. Increased production reduced silver's perceived value, so that gold gradually replaced it as a monetary standard. Silver continued to be used in ornaments, tableware and some coins.

Today, photographic paper and film, followed by the electronics and jewellery/ tableware industries are the most important users of silver. Other uses are in brazing alloys, solder, mirrors, medicines, tooth fillings, coins and medallions.

I have seen a few other posts in sci.chem, however, you may wish to also
consider Brashear's Glass Silvering Process, as described in the browned
and well thumbed pages of my CRP Handbook of Chemistry and Physics, 26th
Ed, 1942, pp. 2397-8.

- - - - - - - - - - - -  - - - - -  - - - - -  - - - - -  - - - -  - - -

Two solutions are required, one, the reducing solution, should be prepared
at least a week before it is used, and it may be made in large quantity and
kept in stock with advantage; the other solution is to be prepared when
used.

Reducing solution:  Dissolve 80 gm pure sugar (granulated) in 700 cc of
distilled water.  Add 175 cc alcohol, 3 cc nitric acid (1.42 sg), and
complete to 1000 cc with distilled water.

For silvering, the mirror may rest face up on the bottom of a suitable
dish; it may stand on edge, or be supported in any manner, face downward,
dipping into the upper part of the solution.  In the latter case, the
mirror may be fastened with wax to a stick laid across the dish, or it may
be supported on glass feet or on paraffined wood wedges.  Dr. Brashear
recommends that the mirror, if round, form the bottom of the silvering
dish, which is completed by wrapping a strip of paraffined paper around the
edge of the mirror, this being held in place by rubber bands or fastened
with several wrappings of cord.

Having selected a dish and support for the mirror, measure with water the
quantity of solution that will be required to make a layer a centimeter or
two thick over the surface to be silvered.  For each 150 cc of final
solution, 1 gm of silver nitrate and 0.5 gm of caustic potash (alcohol
purified) will be required.  Dissolve the silver and potash separately,
using quantities of water of the proportion of 100 cc to 1 gm of solid.
Ordinary graduates or flasks are the most convenient form of vessel in
which to mix the solutions.  Into the silver nitrate solution pour a few
drops of dilute aqua ammonia.  The solution will turn to a dark brown
color; add ammonia li... [pop]

Additional information on all elements can be found through the following links:

is a link to the Web Elements page.

The University of Illinois at Chicago Thermodynamics Research Laboratory offers a compilation of Thermodynamic Data and Property sites.

The Los Alamos National Laboratory provides an online Periodic Table with supporting data.