You just dug up an old coin—now what? Identifying coins found metal detecting is part science, part detective work. That crusty disc covered in dirt could be a common wheat penny or a valuable colonial copper worth thousands.
This guide covers everything you need to know about identifying the old coins you find while metal detecting, from initial cleaning to determining value.
Step 1: Initial Assessment (Don’t Clean Yet!)
Critical Rule: Never aggressively clean a coin before you know what it is. Cleaning can destroy value—a coin worth $1,000 can become worth $10 after improper cleaning.
What to Look For First
- Size: Measure diameter in millimeters
- Metal color: Copper, silver, gold, or bronze tone?
- Edge: Smooth, reeded (ridged), or lettered?
- Thickness: Thick like a half dollar or thin like a dime?
- Any visible design elements: Eagle, portrait, shield, date?
Step 2: Gentle Initial Cleaning
For initial identification only—use only these safe methods:
- Rinse with distilled water (not tap water—mineral deposits can damage coins)
- Gently rub with wet fingers to remove loose dirt
- Pat dry with soft cloth—don’t rub
- Use a magnifying glass to examine details
Do NOT:
- Use metal brushes or abrasives
- Soak in chemicals without knowing the metal type
- Scrub with toothbrush (even soft bristles can scratch)
Step 3: Identify by Size
Common U.S. Coin Sizes
| Denomination | Diameter | Edge |
|---|---|---|
| Cent (modern) | 19.0 mm | Plain |
| Large Cent (1793-1857) | 27-29 mm | Plain |
| Nickel | 21.2 mm | Plain |
| Dime | 17.9 mm | Reeded |
| Quarter | 24.3 mm | Reeded |
| Half Dollar | 30.6 mm | Reeded |
| Dollar (Morgan/Peace) | 38.1 mm | Reeded |
Step 4: Identify by Design
U.S. Penny Designs
- Lincoln Wheat (1909-1958): Lincoln portrait, wheat ears on reverse
- Indian Head (1859-1909): Native American headdress design
- Flying Eagle (1856-1858): Eagle in flight—rare!
- Large Cents (1793-1857): Various Liberty head designs, larger than modern pennies
U.S. Dime Designs
- Roosevelt (1946-present): FDR portrait
- Mercury (1916-1945): Winged Liberty head (often mistaken for Mercury god)
- Barber (1892-1916): Liberty with cap
- Seated Liberty (1837-1891): Liberty seated on rock
U.S. Quarter Designs
- Washington (1932-present): George Washington portrait
- Standing Liberty (1916-1930): Liberty standing with shield
- Barber (1892-1916): Liberty with cap
- Seated Liberty (1838-1891): Liberty seated design
Step 5: Check the Date
Key Dates That Mean Value
Wheat Pennies:
- 1909-S VDB: $700-$2,000+
- 1914-D: $200-$500+
- 1922 No D: $500-$1,000+
- 1931-S: $40-$100+
- 1955 Double Die: $1,000-$10,000+
Mercury Dimes:
- 1916-D: $500-$2,000+
- 1921: $50-$200+
- 1921-D: $75-$300+
Standing Liberty Quarters:
- 1916: $2,000-$10,000+
- 1918/7-S: $1,500-$5,000+
Step 6: Determine if It’s Silver
Quick Silver Tests
U.S. coins that contain silver:
- Dimes, quarters, half dollars dated 1964 or earlier = 90% silver
- Kennedy half dollars 1965-1970 = 40% silver
- War nickels 1942-1945 (with large mint mark above Monticello) = 35% silver
Visual Test: Look at the edge. Silver coins are solid silver color throughout. Clad coins show a copper stripe.
Weight Test:
- Silver quarter: 6.25 grams
- Clad quarter: 5.67 grams
- Silver dime: 2.5 grams
- Clad dime: 2.27 grams
Step 7: Research and Value
Free Resources
- NGC Coin Price Guide: ngccoin.com/price-guide
- PCGS CoinFacts: pcgs.com/coinfacts
- USA Coin Book: usacoinbook.com
- CoinTrackers: cointrackers.com
When to Get Professional Grading
Consider professional grading (PCGS or NGC) if:
- The coin appears to be a key date
- It’s in excellent condition (minimal wear)
- Initial research suggests value over $100
- You want to sell the coin
Common Finds and What They’re Worth
| Find | Typical Value | Notes |
|---|---|---|
| Common wheat penny | $0.05-$0.25 | Check date for key dates |
| Indian Head penny | $1-$10 | More in better condition |
| Silver Roosevelt dime | $2-$3 | Silver melt value |
| Mercury dime | $3-$10 | Check for 1916-D! |
| Silver Washington quarter | $5-$7 | Silver melt value |
| Barber dime/quarter | $5-$50+ | Condition critical |
| Large cent | $20-$100+ | Date/type dependent |
What If You Can’t Identify It?
If the coin is too worn or corroded to identify:
- Post photos to forums: TreasureNet, DetectorProspector, Reddit r/metaldetecting
- Visit a local coin shop: Most will identify for free
- Join a metal detecting club: Experienced members love helping identify finds
- Use Google Lens: Take a photo and search—surprisingly effective
Protecting Your Valuable Finds
- Don’t carry loose in pocket: Coins scratch each other
- Use 2×2 cardboard flips: Cheap protection for organization
- Store in dry location: Humidity causes corrosion
- Never store in PVC holders: PVC damages coins over time
Found something interesting? Share your find photos in the comments below!
