Coin Metals and Compositions
Use metal, alloy, weight, color, corrosion, and manufacturing evidence to refine attribution.
Copper Coins
Color, porosity, verdigris, planchet quality, and natural versus altered surfaces.
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Bronze Coins
Alloy variation, patina, corrosion, and historic circulation.
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Brass Coins and Tokens
Yellow-metal alloys, toning, corrosion, and token crossover.
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Nickel Coins
Hard alloy strikes, hairlines, spots, and magnetic or composition checks.
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Copper-Nickel Coins
Pale alloy coinage, strike quality, cleaning, and metal verification.
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Silver Coins
Fineness, weight, toning, luster, circulation wear, and bullion versus collector value.
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Billon Coins
Low-grade silver alloys, dark surfaces, fragile flans, and historical debasement.
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Gold Coins
Weight, fineness, edge diagnostics, counterfeits, jewelry damage, and certification.
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Electrum Coins
Ancient gold-silver alloy coinage, style, fabric, testing limits, and provenance.
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Aluminum Coins
Lightweight coinage, oxidation, handling marks, and early modern issues.
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Zinc Coins
White corrosion, wartime alloys, plating, and storage concerns.
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Iron and Steel Coins
Magnetism, rust, plating loss, wartime issues, and conservation.
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Bimetallic Coins
Ring-and-core construction, alignment, separation, and modern world issues.
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Plated Coins
Core exposure, plating bubbles, counterfeit plating, and modern compositions.
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