Vote for your favorite mineral in #MinCup26! - Hafnon vs. Putnisite
It's a pair of tiny minerals of unusual chemistry as orange Hafnon battles with purple Putnisite.
Log InRegister
Quick Links : The Mindat ManualThe Rock H. Currier Digital LibraryMindat Newsletter [Free Download]
Home PageAbout MindatThe Mindat ManualHistory of MindatCopyright StatusWho We AreContact UsAdvertise on Mindat
Donate to MindatCorporate SponsorshipSponsor a PageSponsored PagesMindat AdvertisersAdvertise on Mindat
Learning CenterWhat is a mineral?The most common minerals on earthInformation for EducatorsMindat ArticlesThe ElementsThe Rock H. Currier Digital LibraryGeologic TimeExplore Fossils
Minerals by PropertiesMinerals by ChemistryMineral Visual ExplorerAdvanced Locality SearchRandom MineralRandom LocalitySearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
Keyword(s):
 
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
Mining CompaniesStatisticsUsersMineral MuseumsClubs & OrganizationsMineral Shows & EventsThe Mindat DirectoryDevice SettingsThe Mineral QuizTime Machine
Photo SearchPhoto GalleriesSearch by ColorPhoto Colour ExplorerNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day GalleryPhotography

Portola Valley, San Mateo County, California, USAi
Regional Level Types
Portola ValleyTown
San Mateo CountyCounty
CaliforniaState
USACountry

This page is currently not sponsored. Click here to sponsor this page.
PhotosMapsSearch
Latitude & Longitude (WGS84):
37° 23' 3'' North , 122° 14' 7'' West
Latitude & Longitude (decimal):
37.38417,-122.23528
GeoHash:
G#: 9q9hdmwfx
GRN:
N25W71
Type:
Town
Köppen climate type:
Csb : Warm-summer Mediterranean climate
Mindat Locality ID:
227025
Long-form identifier:
mindat:1:2:227025:1
GUID (UUID V4):
0


A populated place (town) in a valley of the same name, located on the San Andreas Fault rift zone.

Select Mineral List Type

Standard Detailed Gallery Strunz Chemical Elements

Commodity List

This is a list of exploitable or exploited mineral commodities recorded from this region.


Mineral List

Mineral list contains entries from the region specified including sub-localities

6 valid minerals.

Rock Types Recorded

Note: data is currently VERY limited. Please bear with us while we work towards adding this information!

Rock list contains entries from the region specified including sub-localities

Select Rock List Type

Alphabetical List Tree Diagram

Detailed Mineral List:

ⓘ Calomel
Formula: [Hg2]2+Cl2
ⓘ Cinnabar
Formula: HgS
ⓘ Eglestonite
Formula: [Hg2]2+3OCl3(OH)
ⓘ Galena
Formula: PbS
Description: Occurs as a 30 inch (76.5 cm) thick vein.
ⓘ Mercury
Formula: Hg
ⓘ Quartz
Formula: SiO2
ⓘ 'Serpentine Subgroup'
Formula: D3[Si2O5](OH)4

Gallery:

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
ⓘMercury1.AD.05Hg
Group 2 - Sulphides and Sulfosalts
ⓘGalena2.CD.10PbS
ⓘCinnabar2.CD.15aHgS
Group 3 - Halides
ⓘCalomel3.AA.30[Hg2]2+Cl2
ⓘEglestonite3.DD.05[Hg2]2+3OCl3(OH)
Group 4 - Oxides and Hydroxides
ⓘQuartz4.DA.05SiO2
Unclassified
ⓘ'Serpentine Subgroup'-D3[Si2O5](OH)4

List of minerals for each chemical element

HHydrogen
Hⓘ Eglestonite[Hg2]32+OCl3(OH)
Hⓘ Serpentine SubgroupD3[Si2O5](OH)4
OOxygen
Oⓘ Eglestonite[Hg2]32+OCl3(OH)
Oⓘ QuartzSiO2
Oⓘ Serpentine SubgroupD3[Si2O5](OH)4
SiSilicon
Siⓘ QuartzSiO2
Siⓘ Serpentine SubgroupD3[Si2O5](OH)4
SSulfur
Sⓘ CinnabarHgS
Sⓘ GalenaPbS
ClChlorine
Clⓘ Calomel[Hg2]2+Cl2
Clⓘ Eglestonite[Hg2]32+OCl3(OH)
HgMercury
Hgⓘ Calomel[Hg2]2+Cl2
Hgⓘ CinnabarHgS
Hgⓘ Eglestonite[Hg2]32+OCl3(OH)
Hgⓘ MercuryHg
PbLead
Pbⓘ GalenaPbS

Other Databases

Wikipedia:https://en.wikipedia.org/wiki/Portola_Valley,_California
Wikidata ID:Q1011116

Localities in this Region

USA

Other Regions, Features and Areas containing this locality

North AmericaContinent
North America Plate
Pacific PlateTectonic Plate

This page contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.
Quick NavTopCommoditiesMineral ListRock TypesOther DatabasesLocalities in RegionOther Regions
 
and/or  
Mindat.org® is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization. Mindat® and mindat.org® are registered trademarks of the Hudson Institute of Mineralogy.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2026, except where stated. Most political location boundaries are © OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters. Founded in 2000 by Jolyon Ralph and Ida Chau.
Content on this site may not be used to train, fine-tune, or otherwise develop artificial intelligence or machine learning models without prior written permission - see our Terms & Conditions.
To cite: Ralph, J., Von Bargen, D., Martynov, P., Zhang, J., Que, X., Prabhu, A., Morrison, S. M., Li, W., Chen, W., & Ma, X. (2025). Mindat.org: The open access mineralogy database to accelerate data-intensive geoscience research. American Mineralogist, 110(6), 833–844. doi:10.2138/am-2024-9486.
Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: September 9, 2026 00:48:24 Page updated: July 18, 2025 10:06:27
Go to top of page