In both astrology and astronomy, the zodiac is a circle of twelve 30° divisions of celestial longitude. The division of the ecliptic (the path of the sun relative to the earth) into the zodiacal signs originates in Babylonian somewhere around 700BC. Names of constellations of stars are associated with the Zodiac, such as Aries, Taurus, Gemini, and 9 others.
The signs of the zodiac are a favorite theme for modern coins, tokens, and medals. Some countries have issued coins with signs of the zodiac, and countless private mints have produced tokens and medals these depictions. A Google search for 'zodiac tokens' produces hundreds of different patterns, many of them are sexually explicit.
These are modern pieces and their numismatic (coin collector) value depends only on the amount of precious metal they contain. People involved with astrology would likely pay more than metal value, but most coin dealers are not swayed by such considerations and pay only base value for these pieces.
Here are two 'rules of thumb' for evaluating zodiac coins, tokens, and medals.
1. If the piece is made of gold or silver, it is worth its weight in precious metal. Determining the amount of precious metal in a piece involves knowing its weight (easy) and its purity (hard). Sterling silver, for instance, is 92.5 percent pure, so a coin weighing 25 grams contains 0.925 x 25 = 23.1 grams of silver. Consult a jeweler if you are unsure of purity. Once you know the amount of gold or silver, convert it to troy ounces (there are 31.1 grams in one troy ounce) and go to kitco.com to find the value in US dollars per troy ounce. Do the multiplication, and that is the value of your zodiac piece.
2. If your zodiac piece is made of brass, nickel, pewter, zinc, or other non-precious metal, it is worth between $2 and $20, depending on design, overall appeal, and amount of wear.