For eBay buyers who may be interested in purchasing circulated coins from Australia, at least in part for their metal content - as silver bullion - here is a quick guide.

Overview

From the perspective of a silver coin buyer on eBay, there have been three distinct eras of Australian coins since 1910:

• Prior to 1946, Australian pre-decimal silver coins contained high purity, 92.5% (Sterling) silver.
• From 1946 to 1963, Australian pre-decimal silver coins contained 50% silver.
• From 1966-on, some denominations of Australian decimal coins issued for circulation were "silver-colored," however these coins were made of copper-nickel, and contained no silver.  There was one notable exception: in 1966 (only), the 50 cent coin contained 80% silver. In addition, there have been some silver decimal coins minted in limited quantities as commemorative or bullion issues, which were not intended for circulation.
  

The standard circulating denominations of pre-decimal Australian coins from 1910 to 1963 which contained 92.5% or 50% silver, included threepences, sixpences, shillings, florins, and crowns.

Prior to 1946

Prior to 1946, Australian silver coins contained high purity, 92.5% (Sterling) silver.  These coins contain the following amounts of actual silver weight:

• Threepence (.0419 Troy ounces of actual silver weight)
• Six pence (.0838 Troy ounces)
• Shilling (.1680 Troy ounces)
• Florin (.3363 Troy ounces)
• Crown (issued in 1937-1938 only) (.8411 Troy ounces)

All the silver weights above are for as-minted, uncirculated coins.  Circulated coins will weigh somewhat less overall and thus have modestly less silver content than listed above.

From 1946 to 1963

From 1946 to 1963, Australian silver coins contained 50% silver.  These coins contain the following amounts of actual silver weight:

• Threepence (.0226 Troy ounces of actual silver weight)
• Six pence (.0453 Troy ounces)
• Shilling (.0908 Troy ounces)
• Florin (.1818 Troy ounces)

All the silver weights above are for as-minted, uncirculated coins.  Circulated coins will weigh somewhat less overall and thus have modestly less silver content than listed above.

A few 1951 Florins were minted in copper-nickel: In 1951, on the occasion of the royal visit of Queen Elizabeth II to Australia, the "Royal Visit" commemorative Florin was not only minted for circulation in silver, but also was struck - in Proof only - in copper-nickel.  Those coins are rare and highly valued by collectors.

Other than that one exception, however, all Australian threepence through florin coins from 1946 to 1963 were minted for circulation with 50% silver content.

From 1966-on

From 1966-on, Australian decimal coins issued for day-to-day circulation were made of copper-nickel or other metals, and contained no silver, with one notable exception below.  Since many denominations of these coins are "silver-colored," a few eBay sellers might mistakenly identify these coins as silver in their listings.

The one exception is a single denomination - in a single year, no less - which was minted for circulation in 80% silver:

• 50 cents (1966 only) (.3416 Troy ounces of actual silver weight)

All subsequent dates of Australian 50 cent pieces, from 1969-on, have been minted only in copper-nickel, not silver.  Only the 1966 50 cent pieces contained silver.

A small number of Australian decimal coins beginning in the 1980s have contained silver, but these have generally been commemorative or bullion coins minted in limited quantities, not intended for circulation.  One notable example is the series of 1, 2, 5, and 10 Dollar silver bullion coins issued since the early 1990s, bearing the Kookaburra bird or (occasionally) the Kangaroo as subjects.