Farm Hill No. 2 Mine (Emerald Lake Mine; Upper Emerald Lake deposit; Farm Hill Cinnabar property), Redwood City, San Mateo County, California, USAi
| Regional Level Types | |
|---|---|
| Farm Hill No. 2 Mine (Emerald Lake Mine; Upper Emerald Lake deposit; Farm Hill Cinnabar property) | Mine |
| Redwood City | City |
| San Mateo County | County |
| California | State |
| USA | Country |
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Latitude & Longitude (WGS84):
37° 27' 12'' North , 122° 15' 1'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Emerald Lake Hills | 4,278 (2011) | 2.0km |
| Woodside | 5,561 (2017) | 2.6km |
| Redwood City | 85,288 (2017) | 3.7km |
| Atherton | 7,167 (2017) | 4.7km |
| West Menlo Park | 3,659 (2011) | 4.7km |
Nearest Clubs:
Local clubs are the best way to get access to collecting localities
Local clubs are the best way to get access to collecting localities
| Club | Location | Distance |
|---|---|---|
| Sequoia Gem and Mineral Society | Redwood City, California | 4km |
| Peninsula Gem & Geology Society, Inc. | Los Altos, California | 14km |
| Mineral & Gem Society of Castro Valley | Hayward, California | 28km |
| East Bay Mineral and Lapidary Club | Hayward, California | 28km |
| Santa Clara Valley Gem & Mineral Society | San Jose, California | 34km |
A former Hg occurrence/mine located in the W½ sec. 36, T5S, R4W, MDM, 3.8 km (2.3 miles) SSW of Redwood City center, just inside the city boundary in Stulsaft Park, on private land (?). MRDS database stated accuracy for this location is .
Local rocks include ultramafic rocks, chiefly Mesozoic, unit 3 (Coast Ranges and Western Klamath Mountains).
The existence of mercury mineralization at the site has been known since 1863, but only after being rediscovered in 1953 during site work for a housing development, was it mined.
Fragments of cinnabar and metacinnabar were found in top soil. The area is in the central part of an irregular mass of serpentine, which at the surface has weathered to an ocherous clay. Below this clay, cinnabar coats fracture surfaces in silica-carbonate rock and the surrounding tuff and shale of the Franciscan formation. Cinnabar, metacinnabar, and native mercury occur in vugs and along fracture surfaces in the rock.
Eglestonite, terlinguaite, calomel and native mercury are also present in the ore. Very rare wattersite has been identified in some samples (R. Erd, 1990). Montroydite rarely occurs with the native mercury. The area is now largely covered by streets and houses, but some cinnabar-bearing exposures are in an adjoining city park.
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsCommodity List
This is a list of exploitable or exploited mineral commodities recorded at this locality.Mineral List
8 valid minerals.
Detailed Mineral List:
| ⓘ Calomel Formula: [Hg2]2+Cl2 References: |
| ⓘ Cinnabar Formula: HgS Description: Occurs in vugs in silica-carbonate rock. References: |
| ⓘ Eglestonite Formula: [Hg2]2+3OCl3(OH) References: |
| ⓘ Magnesiochromite Formula: MgCr2O4 References: |
| ⓘ Metacinnabar Formula: HgS Description: Occurs in vugs in silica-carbonate rock. References: |
| ⓘ Native Mercury Formula: Hg Description: Occurs in vugs in silica-carbonate rock. References: |
| ⓘ Terlinguaite Formula: [Hg3]4+Hg2+Cl2O2 |
| ⓘ Wattersite Formula: [Hg2]2+2Hg2+[CrO4]O2 References: |
List of minerals arranged by Strunz 10th Edition classification
| Group 1 - Elements | |||
|---|---|---|---|
| ⓘ | Native Mercury | 1.AD.05 | Hg |
| Group 2 - Sulphides and Sulfosalts | |||
| ⓘ | Metacinnabar | 2.CB.05a | HgS |
| ⓘ | Cinnabar | 2.CD.15a | HgS |
| Group 3 - Halides | |||
| ⓘ | Calomel | 3.AA.30 | [Hg2]2+Cl2 |
| ⓘ | Eglestonite | 3.DD.05 | [Hg2]2+3OCl3(OH) |
| ⓘ | Terlinguaite | 3.DD.20 | [Hg3]4+Hg2+Cl2O2 |
| Group 4 - Oxides and Hydroxides | |||
| ⓘ | Magnesiochromite | 4.BB.05 | MgCr2O4 |
| Group 7 - Sulphates, Chromates, Molybdates and Tungstates | |||
| ⓘ | Wattersite | 7.FB.15 | [Hg2]2+2Hg2+[CrO4]O2 |
List of minerals for each chemical element
| H | Hydrogen | |
|---|---|---|
| H | ⓘ Eglestonite | [Hg2]32+OCl3(OH) |
| O | Oxygen | |
| O | ⓘ Eglestonite | [Hg2]32+OCl3(OH) |
| O | ⓘ Magnesiochromite | MgCr2O4 |
| O | ⓘ Terlinguaite | [Hg3]4+Hg2+Cl2O2 |
| O | ⓘ Wattersite | [Hg2]22+Hg2+[CrO4]O2 |
| Mg | Magnesium | |
| Mg | ⓘ Magnesiochromite | MgCr2O4 |
| S | Sulfur | |
| S | ⓘ Cinnabar | HgS |
| S | ⓘ Metacinnabar | HgS |
| Cl | Chlorine | |
| Cl | ⓘ Calomel | [Hg2]2+Cl2 |
| Cl | ⓘ Eglestonite | [Hg2]32+OCl3(OH) |
| Cl | ⓘ Terlinguaite | [Hg3]4+Hg2+Cl2O2 |
| Cr | Chromium | |
| Cr | ⓘ Magnesiochromite | MgCr2O4 |
| Cr | ⓘ Wattersite | [Hg2]22+Hg2+[CrO4]O2 |
| Hg | Mercury | |
| Hg | ⓘ Calomel | [Hg2]2+Cl2 |
| Hg | ⓘ Cinnabar | HgS |
| Hg | ⓘ Eglestonite | [Hg2]32+OCl3(OH) |
| Hg | ⓘ Native Mercury | Hg |
| Hg | ⓘ Metacinnabar | HgS |
| Hg | ⓘ Terlinguaite | [Hg3]4+Hg2+Cl2O2 |
| Hg | ⓘ Wattersite | [Hg2]22+Hg2+[CrO4]O2 |
Other Databases
| Link to USGS MRDS: | 10077428 |
|---|
Other Regions, Features and Areas containing this locality
North AmericaContinent
- Coast MountainsMountain Range
North America PlateTectonic Plate
- California Coast RangesAccretionary Complex
- Franciscan DomainDomain
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Farm Hill No. 2 Mine, Redwood City, San Mateo County, California, USA