How a Printing Error Created One of America’s Most Valuable Modern Coins
This extraordinary Washington Quarter/Sacagawea Dollar mule error represents one of the rarest and most valuable mint mistakes in U.S. history. Here’s everything you need to know about this numismatic phenomenon worth nearly $200,000.
What Makes This Coin So Valuable?
The “Mule Error” Explained
- Definition: A coin struck with mismatched obverse and reverse dies
- This Specific Error:
- Obverse (Heads): Standard Washington quarter design
- Reverse (Tails): Sacagawea dollar eagle reverse
- Rarity: Only 3 confirmed specimens known to exist
Key Identification Features
| Feature | Correct Quarter | Mule Error |
|---|---|---|
| Diameter | 24.26mm | 26.50mm (dollar size) |
| Edge | Reeded (119 reeds) | Plain (like dollars) |
| Weight | 5.67g | 8.10g (dollar weight) |
| Reverse Design | Quarter eagle | Dollar eagle |
Grading & Market Value
Population Report
| Grading Service | Grade | Known Examples |
|---|---|---|
| PCGS | MS66 | 1 |
| NGC | MS67 | 2 |
Recent Sales History
- $195,000: PCGS MS66 (Heritage Auctions, 2023)
- $192,000: NGC MS67 (Stack’s Bowers, 2022)
- Private Sale: NGC MS67 (~$200,000, 2024)
How This Error Occurred
Mint Production Mishap
- Die Mix-Up: Quarter obverse die mistakenly paired with dollar reverse die
- Press Configuration: Used dollar coin press (explains larger size)
- Quality Control Failure: Missed during inspection process
- Circulation Escape: Estimated 5-10 may exist (only 3 confirmed)
How to Spot Potential Mules
Examination Checklist
- Size Test: Compare to normal quarter (should be larger)
- Weight Check: Must be ~8.10g (use precision scale)
- Edge Inspection: Should be smooth (not reeded)
- Reverse Verification: Match to Sacagawea dollar design
Warning Signs of Fakes
❌ Gold plating (real mules aren’t gold-colored)
❌ Wrong weight/size
❌ Evidence of tooling or alteration
Where to Search for Undiscovered Specimens
Best Hunting Grounds
- 2000-D Mint Sets (original source of known examples)
- Coin Roll Hunting: $10 quarter rolls from Denver mint
- Estate Collections: Look for unusual 2000s-era holdings
Recent Discovery:
A Nevada collector found one in an unopened mint set purchased at a garage sale for $5
If You Find a Potential Mule
Critical First Steps
- Don’t Clean! (preserve original surfaces)
- Handle by Edges Only (use cotton gloves)
- Document Everything (take timestamped photos)
- Secure Storage (bank safety deposit box recommended)
Professional Authentication
- PCGS/NGC Submission Required ($150+ fee)
- XRF Metal Testing (verify composition)
- Provenance Research (essential for high-value coins)
Where to Sell for Maximum Value
Best Auction Houses
- Heritage Auctions (record-setting sales)
- Stack’s Bowers (specializes in errors)
- Legend Rare Coin Auctions (private treaty sales)
Selling Tip:
Certified coins sell for 200-300% more than raw examples
Free Professional Evaluation
Think you’ve found a mule error? Email clear photos to:
📧 errors@pennyverse.info
Subject: “QUARTER MULE CHECK”
We’ll provide:
✔ Free preliminary assessment
✔ Current market valuation
✔ Next-step recommendations
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