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Silver
Mohs 2.5–3. Native silver tarnishes black. Mindat
12 sites
Copper
Mohs 2.5–3. Native copper is soft and turns green as it weathers. Mindat
11 sites
Gold
Mohs 2.5–3. Soft, heavy and bright yellow; it doesn’t tarnish. Mindat
7 sites
Pyrite
Mohs 6–6.5. Brassy “fool’s gold,” often cubic. Mindat
2 sites
Quartz
Mohs 7. Six-sided points; smoky quartz is NH’s state gem. Mindat
1 site
Counts are sites whose USGS record mentions the mineral or commodity. Hardness from Mindat.
By county
Frederick County (11) · Baltimore city (1)
Sites
| Site | Commodity | Minerals recorded | Status | Approx. location |
|---|---|---|---|---|
| Liberty Mine | Copper | — | Past Producer | 39.513, -77.254 |
| Dolly Hyde Mine | Copper | — | Past Producer | 39.479, -77.227 |
| New London Mine Linganore | Copper | — | Past Producer | 39.421, -77.258 |
| Frederick Gold Mine | Gold, Silver | — | Past Producer | 39.417, -77.491 |
| Cox Mines | — | — | Prospect | 39.551, -77.205 |
| New London Mine | — | — | Past Producer | 39.419, -77.260 |
| Mountain View Mine | — | — | Prospect | 39.547, -77.202 |
| Hines Prospects | — | — | Prospect | 39.480, -77.250 |
| Hammond Prospect | — | — | Past Producer | 39.473, -77.249 |
| Eiler Prospect | — | — | Prospect | 39.541, -77.203 |
| American Smelt & Refin/Baltimore Md | Gold | — | Plant | 39.290, -76.609 |
| Liberty Mine | — | — | Past Producer | 39.513, -77.254 |
Back to Rockhounding in Maryland.
How we built this page: we counted named sites in the USGS Mineral Resources Data System (MRDS) for this area, left out sand, gravel, crushed stone, clay pits and unnamed sites, grouped them by Census county, and linked every site to its USGS record. We did not visit these sites, and MRDS does not tell you who owns the land or whether collecting is allowed.
Source: USGS Mineral Resources Data System (MRDS). USGS ceased systematic updates to MRDS around 2011, so status and details may be out of date. Each site links to its USGS record.
Updated