New Almaden
Also known as: New Almaden Historic District
Why it's listed
New Almaden is a former mercury mining town south of San Jose, California, now a quiet residential village along a wooded creek canyon. The settlement grew around the first quicksilver deposit discovered in North America, which was claimed in 1845 by Andreas Castillero. Under Henry W. Halleck, large-scale production began in 1850, and output reached about a million pounds a year by 1854. Because quicksilver was used to recover gold and silver from ore, the mine supplied the California gold fields and the Comstock Lode, and by 1865 it provided 60 percent of mercury consumed in California and Nevada. Surviving features include Casa Grande, the 1850s superintendent's residence of adobe and brick, early adobes, board-and-batten miners' cottages, a toll house and St. Anthony's Church of 1900. On Mine Hill, a school, store walls, brick chimneys, flumes and shafts remain. The area was recognized as a historic district for its central role in the mining frontier.
Significance in brief: The New Almaden Mine was the first quicksilver deposit discovered in North America and one of the world's four major sources of quicksilver. Its mercury enabled the rapid growth of gold and silver quartz mining in California and the Comstock Lode in Nevada. It is California's oldest mine and its most valuable single mine, producing over $70,000,000 in quicksilver.
Machine-generated summary. This summary was generated by a language model from the official nomination document and has not been reviewed line by line by an editor. It may contain errors. Check the source document before relying on any detail. Source: nomination document (PDF) · National Archives catalog entry. NRHP reference 66000236, listed October 15, 1966. Summary generated October 2026 (model claude-sonnet-5-5, prompt v1.0-2026-10-29, confidence medium).
Key facts
| Address | 14 mi. S of San Jose on CR G8, San Jose |
|---|---|
| County | Santa Clara County |
| Listed | October 15, 1966 |
| Reference number | 66000236 |
| Resource type | District |
| Period of significance | 1845 to present |
| Areas of significance | Industry |
| Level of significance | National |
| National Historic Landmark | Yes, designated July 4, 1961 |
| Status (as stated in the nomination) | Town is now a largely residential village; Casa Grande operates as a club, a museum occupies an adobe, and Mine Hill is closed to visitors because of old shafts. The mine was worked sporadically, and Mine Hill School has been vacant since 1940. |
| Acreage | 3200 |
| Coordinates | 37.17842, -121.81951 (NPS GIS) |
What listing means for this property
This is a historic district. Buildings within its boundary are either contributing (they add to the district's significance) or non-contributing. Owners of contributing income-producing buildings can claim the 20% federal rehabilitation tax credit; homeowners should look at state credits. National Register districts impose no design review by themselves; a local historic district ordinance, if one exists, does (the difference explained).
General information, not legal or tax advice. Rules change; confirm with your State Historic Preservation Office or a qualified adviser.
Sources and further reading
- National Park Service, National Register of Historic Places database (snapshot May 2026), reference 66000236.
- Nomination form (PDF, National Archives) — catalog entry
- Wikipedia article (used for cross-checking only; text not reproduced here)
- Wikidata Q7005296
- This listing as JSON
Last updated October 2026. Found an error? See the editorial policy for how to report it.