RockWoofBest regions by county
Ranked by the number of USGS-recorded sites, not by access or quality.
- Dubuque County: 37 sites; most recorded: Galena, Sphalerite, Limonite
- Clayton County: 28 sites; most recorded: Galena, Smithsonite, Fluorite
- Jackson County: 12 sites; most recorded: Galena, Sphalerite
- Allamakee County: 10 sites; most recorded: Galena, Smithsonite, Hematite
- Marion County: 7 sites; most recorded: Sphalerite
Top minerals
- Sphalerite: 48 sites
- Galena: 45 sites
- Smithsonite: 4 sites
- Barite: 4 sites
- Fluorite: 3 sites
- Pyrite: 3 sites
- Limonite: 3 sites
- Hematite: 2 sites
Mineral cards
Galena
Mohs 2.5–2.75. Heavy, silvery lead ore that breaks into cubes. Mindat
45 sites
Pyrite
Mohs 6–6.5. Brassy “fool’s gold,” often cubic. Mindat
19 sites
Quartz
Mohs 7. Six-sided points; smoky quartz is NH’s state gem. Mindat
13 sites
Fluorite
Mohs 4. Cubes in purple, green or yellow; many glow under UV. Mindat
3 sites
Copper
Mohs 2.5–3. Native copper is soft and turns green as it weathers. Mindat
1 site
Counts are sites whose USGS record mentions the mineral or commodity. Hardness from Mindat.
Minerals most often recorded
Sphalerite 48Galena 45Smithsonite 4Barite 4Fluorite 3Pyrite 3Limonite 3Hematite 2Hemimorphite 1Counties
| County | Sites |
|---|---|
| Dubuque County | 37 |
| Clayton County | 28 |
| Jackson County | 12 |
| Allamakee County | 10 |
| Marion County | 7 |
| Mahaska County | 7 |
| Wapello County | 7 |
| Jasper County | 7 |
| Appanoose County (fewer than 5 sites, no page) | 4 |
| Davis County (fewer than 5 sites, no page) | 4 |
| Jones County (fewer than 5 sites, no page) | 3 |
| Polk County (fewer than 5 sites, no page) | 3 |
| Fayette County (fewer than 5 sites, no page) | 2 |
| Delaware County (fewer than 5 sites, no page) | 2 |
| Black Hawk County (fewer than 5 sites, no page) | 2 |
| Monroe County (fewer than 5 sites, no page) | 2 |
| Winneshiek County (fewer than 5 sites, no page) | 2 |
| Scott County (fewer than 5 sites, no page) | 2 |
| Lee County (fewer than 5 sites, no page) | 2 |
| Bremer County (fewer than 5 sites, no page) | 1 |
| Linn County (fewer than 5 sites, no page) | 1 |
| Lucas County (fewer than 5 sites, no page) | 1 |
| Clarke County (fewer than 5 sites, no page) | 1 |
| Clinton County (fewer than 5 sites, no page) | 1 |
| Jefferson County (fewer than 5 sites, no page) | 1 |
| Des Moines County (fewer than 5 sites, no page) | 1 |
| Story County (fewer than 5 sites, no page) | 1 |
| Hardin County (fewer than 5 sites, no page) | 1 |
| Muscatine County (fewer than 5 sites, no page) | 1 |
| Warren County (fewer than 5 sites, no page) | 1 |
| Adair County (fewer than 5 sites, no page) | 1 |
| Iowa County (fewer than 5 sites, no page) | 1 |
| Woodbury County (fewer than 5 sites, no page) | 1 |
Mineral guides
- Quartz in Iowa (13)
- Pyrite in Iowa (19)
- Galena in Iowa (45)
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