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Archstone, Agoura Hills, Los Angeles County, California, USAi
Regional Level Types
Archstone- not defined -
Agoura HillsCity
Los Angeles CountyCounty
CaliforniaState
USACountry

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Latitude & Longitude (WGS84):
34° 8' 17'' North , 118° 47' 33'' West
Latitude & Longitude (decimal):
Nearest Settlements:
PlacePopulationDistance
Westlake Village8,507 (2017)1.5km
Agoura Hills20,915 (2017)1.7km
Agoura20,537 (2006)5.1km
Oak Park13,811 (2011)5.3km
Thousand Oaks129,339 (2017)5.5km
Nearest Clubs:
Local clubs are the best way to get access to collecting localities
ClubLocationDistance
Conejo Gem & Mineral ClubThousand Oaks, California5km
Del Air Rockhounds ClubNorthridge, California26km
Oxnard Gem & Mineral SocietyOxnard, California36km
Sierra Pelona Rock ClubNewhall, California36km
The Culver City Rock and Mineral ClubCulver City, California39km
Mindat Locality ID:
263810
Long-form identifier:
mindat:1:2:263810:5
GUID (UUID V4):
5629b812-f700-41f3-ab75-983816b1eeda


This locality has similar geology to the rest of the Ladyface Mtn area, including marcasite agate and chalcedony in brecciated volcanic rock, mainly andesite. The difference here is the fact that some of the marcasite oxidized into secondary minerals including jarosite, sulfur and gypsum. This is the third occurrence of jarosite and the first confirmed occurrence of elemental sulfur in Santa Monica Mts.

Jarosite occurs as dark brown flat trigonal bipyramid crystals up to 3mm in size throughout the vugs in the white agate. Second-generation jarosite frequently occurs on top of the brown jarosite in sparkly masses of honey yellow color, it is sub-mm size. Sulfur occurs as bright light-yellow sharp euhedral crystals up to 2mm. White powdery gypsum shows up occasionally, in a few places as mm-size euhedral gypsum crystals. Some of the vugs contain bubbly chalcedony covered with strongly iridescent goethite. Vugs exposed to the elements usually contain orange and red limonite.

The area also yielded angelwing agate, lots of gray chalcedony and some quartz crystals that exhibit weird stacks of almost rhombohedral shape crystals.

There is an outcrop a little bit farther off the trail with melanophlogite pseudomorphs in chalcedony vugs in brecciated volcanic rock.

The samples were analyzed by Dr. Housley.

Select Mineral List Type

Standard Detailed Gallery Strunz Chemical Elements

Mineral List

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

6 valid minerals.

Gallery:

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
β“˜Sulphur1.CC.05S8
Group 2 - Sulphides and Sulfosalts
β“˜Marcasite2.EB.10aFeS2
Group 4 - Oxides and Hydroxides
β“˜Goethite4.00.Ξ±-Fe3+O(OH)
β“˜Quartz
var. Agate
4.DA.05SiO2
β“˜var. Chalcedony4.DA.05SiO2
β“˜4.DA.05SiO2
β“˜Opal4.DA.10SiO2 Β· nH2O
Group 7 - Sulphates, Chromates, Molybdates and Tungstates
β“˜Jarosite7.BC.10KFe3+3(SO4)2(OH)6
Unclassified
β“˜'Limonite'-

List of minerals for each chemical element

HHydrogen
Hβ“˜ GoethiteΞ±-Fe3+O(OH)
Hβ“˜ JarositeKFe33+(SO4)2(OH)6
Hβ“˜ OpalSiO2 · nH2O
OOxygen
Oβ“˜ Quartz var. ChalcedonySiO2
Oβ“˜ GoethiteΞ±-Fe3+O(OH)
Oβ“˜ JarositeKFe33+(SO4)2(OH)6
Oβ“˜ OpalSiO2 · nH2O
Oβ“˜ QuartzSiO2
SiSilicon
Siβ“˜ Quartz var. ChalcedonySiO2
Siβ“˜ OpalSiO2 · nH2O
Siβ“˜ QuartzSiO2
SSulfur
Sβ“˜ JarositeKFe33+(SO4)2(OH)6
Sβ“˜ MarcasiteFeS2
Sβ“˜ SulphurS8
KPotassium
Kβ“˜ JarositeKFe33+(SO4)2(OH)6
FeIron
Feβ“˜ GoethiteΞ±-Fe3+O(OH)
Feβ“˜ JarositeKFe33+(SO4)2(OH)6
Feβ“˜ MarcasiteFeS2

Localities in this Region

Other Regions, Features and Areas containing this locality

North America
North America Plate
Pacific PlateTectonic Plate
USA

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