Vote for your favorite mineral in #MinCup26! - Quartz vs. Asagiite
It's a classic vs a newbie as the most common named mineral in the crust Quartz is up against an exceedingly-rare sea foam-green mineral discovered just a few years ago Asagiite.
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

Colby Prospect, Yentna Mining District, Matanuska-Susitna Borough, Alaska, USAi
Regional Level Types
Colby ProspectProspect
Yentna Mining DistrictMining District
Matanuska-Susitna BoroughBorough
AlaskaState
USACountry

This page is currently not sponsored. Click here to sponsor this page.
PhotosMapsSearch
Latitude & Longitude (WGS84):
62° 34' 22'' North , 150° 57' 50'' West
Latitude & Longitude (decimal):
62.57278,-150.96389
GeoHash:
G#: beheuxp2y
GRN:
N42W53
Type:
Prospect
Köppen climate type:
ET : Tundra
Mindat Locality ID:
196982
Long-form identifier:
mindat:1:2:196982:8
GUID (UUID V4):
0


The highest grade lode deposits in Yentna district are Colby, Bird (TL040), and Nugget Creek (TL035) prospects (Hawley and Clark, 1973, p. A6).
Location: C.C. Hawley and Associates, Inc. (1978, Fig. 4.2-B (3)) locate this property in the southeast quarter of Section 28, T. 29 N., R. 9 W., of the Seward Meridian on ridge between Bird and Nugget Creeks.
Geology: At this locality disseminated arsenopyrite occurs in a 4-foot-wide felsite porphyry dike and also in a thin quartz vein, with euhedral quartz and arsenopyrite crystals, that borders the dike (Clark and Hawley, 1968). Alteration adjacent to and within the dike is comprised of muscovite, pitticite, zircon and sericite (Clark and Hawley, 1968). A sample of the felsite porphyry contains 0.80 ppm Au, 5000 ppm As, 1500 ppm Ba, 150 ppm Zr, 50 ppm W (Clark and Hawley, 1968). Regionally Mesozoic marine sedimentary rocks (KJs) are cut by Tertiary (?) felsite dikes (Clark and Hawley, 1968; Reed and Nelson, 1980). Dikes in this prospect area trend N35 to N50E. The highest grade lode deposits in Yentna district are in the Colby, Bird (TL040), and Nugget Creek (TL035) prospects (Hawley and Clark, 1973, p. A6).
Workings: Four or five shallow prospect pits were dug on the property by independant prospectors. In addition reconnaissance mapping, stream silt and rock sampling have been done by the U.S. Geological Survey (Clark and Hawley, 1968; Reed and Nelson, 1980).
Age: Tertiary; mineralization is interpreted to be related to the felsite dikes that are described as Tertiary in age by Clark and Hawley (1968).
Alteration: A thin section of quartz vein shows muscovite, pitticite, zircon and sericite alteration adjacent to and within the dike (Clark and Hawley, 1968).

Commodities (Major) - Au; (Minor) - As
Development Status: No
Deposit Model: Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a).

Select Mineral List Type

Standard Detailed Gallery Strunz Chemical Elements

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.


Mineral List


4 valid minerals.

Gallery:

List of minerals arranged by Strunz 10th Edition classification

Group 2 - Sulphides and Sulfosalts
ⓘArsenopyrite2.EB.20FeAsS
Group 8 - Phosphates, Arsenates and Vanadates
ⓘPitticite8.DB.05(Fe, AsO4, H2O) (?)
Group 9 - Silicates
ⓘZircon9.AD.30Zr(SiO4)
ⓘMuscovite9.EC.15KAl2(AlSi3O10)(OH)2
ⓘvar. Sericite9.EC.15KAl2(AlSi3O10)(OH)2

List of minerals for each chemical element

HHydrogen
Hⓘ MuscoviteKAl2(AlSi3O10)(OH)2
Hⓘ Pitticite(Fe, AsO4, H2O) (?)
Hⓘ Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
OOxygen
Oⓘ MuscoviteKAl2(AlSi3O10)(OH)2
Oⓘ Pitticite(Fe, AsO4, H2O) (?)
Oⓘ ZirconZr(SiO4)
Oⓘ Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
AlAluminium
Alⓘ MuscoviteKAl2(AlSi3O10)(OH)2
Alⓘ Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
SiSilicon
Siⓘ MuscoviteKAl2(AlSi3O10)(OH)2
Siⓘ ZirconZr(SiO4)
Siⓘ Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
SSulfur
Sⓘ ArsenopyriteFeAsS
KPotassium
Kⓘ MuscoviteKAl2(AlSi3O10)(OH)2
Kⓘ Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
FeIron
Feⓘ ArsenopyriteFeAsS
Feⓘ Pitticite(Fe, AsO4, H2O) (?)
AsArsenic
Asⓘ ArsenopyriteFeAsS
Asⓘ Pitticite(Fe, AsO4, H2O) (?)
ZrZirconium
Zrⓘ ZirconZr(SiO4)

Other Databases

Link to USGS - Alaska:TL037

Other Regions, Features and Areas containing this locality

North AmericaContinent
North America 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.

References

C.C. Hawley and Associates, Inc., 1978, Mineral appraisal of lands adjacent to Mt. McKinley National Park, Alaska: U.S. Bureau of Mines Open-File Report 24-78, 277 p., 12 sheets. Clark, A.L., and Cobb, E.H., 1972, Metallic mineral resources map of the Talkeetna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-369, 1 sheet, scale 1:250,000. Clark, A.L., and Hawley, C.C., 1968, Reconnaissance geology, mineral occurrences, and geochemical anomalies of the Yentna district, Alaska: U.S. Geological Survey Open-File Report 68-35, 64 p. Cobb, E.H., and Reed, B.L., 1980, Summaries of data on and lists of reference to metallic and selected nonmetallic mineral deposits in the Talkeetna quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-884, 106 p. Hawley, C.C., and Clark, A.L., 1973, Geology and mineral deposits of the Chulitna -Yentna mineral belt, Alaska: U.S. Geological Survey Professional Paper 758-A, p. A1-A10, 2 plates, scale 1:250,000 and 1:500,000. MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000. Reed, B.L., and Nelson, S.W., 1980, Geologic map of the Talkeetna quadrangle: U.S. Geological Survey Miscellaneous Investigations Map I-1174, 1 sheet, scale 1:250,000. Reed, B.L., Nelson, S.W., Curtin, G.C., and Singer, D.A., 1978, Mineral resources map of the Talkeetna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-870-D, 1 sheet, scale 1:250,000.
Quick NavTopCommoditiesMineral ListOther DatabasesOther RegionsReferences
 
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 6, 2026 02:38:40 Page updated: July 29, 2025 23:34:18
Go to top of page