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Magnolia District, Boulder Co., Colorado, USA

The Magnolia mining district lies, about 5 miles due west of Boulder and about a mile south of Middle Boulder Creek. The district is about 1,400 feet above the valley bottom.

Most of the productive veins crop out in an area of less than a square mile and the outcrops range in altitude from approximately 7,000 feet at the Graphic vein to about 7,700 feet at the Kekionga shaft a mile to the southwest.

Gold-telluride ore was found on the Magnolia vein in 1875 and during the next 2 years nearly all the veins now known in the district were discovered. Because of the high tenor of the ore and its erratic distribution in rich pockets, company mining and milling by absentee landlords has seldom been successful, and the district does not have a large output on record.

All the ore deposits in the Magnolia district are fissure fillings; mineralization has been chiefly of the gold-tel1urille type but some tungsten ore has been mined. Gangue minerals are present in only minor quantity and consist of little but light-colored to dark-colored varieties of extremely fine grained quartz "horn".

The district is noted for the variety of telluride minerals found and for the unusual association of gold tellurides with tungsten, molybdenum, and vanadium minerals.
U.S. Geological Survey Professional Paper 223






Mineral List

Mineral list contains entries from the region specified including sub-localities
Allanite-(Ce)
Altaite
Alunite
Calaverite
Calcite
Calomel
Chalcopyrite
'Chlorite Group'
Coloradoite (TL)
Empressite
Epidote
'Feldspar Group'
Ferberite
'Ferrotellurite' (TL)
Fluorite
'Garnet'
Gold
Hessite
Hübnerite
Ilmenite
var: Picrotitanite

Iodargyrite
Keystoneite (TL)
'Limonite'
Magnolite (TL)
Marcasite
Melonite
Mercury
'Mica Group'
Molybdenite
'Olivine'
Paratellurite
Petzite
Pyrite
Pyrrhotite
Quartz
var: Chalcedony
Rickardite
Roscoelite
'Serpentine Group'
Silver
var: Amalgam
Sphalerite
Stibnite
Sylvanite
Tellurite
Tellurium


55 entries listed. 35 valid minerals. 3 type localities (valid minerals). 1 type locality (other).

Localities in this Region

USA
USA

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References

U.S. Geological Survey Professional Paper 223

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Copyright © Jolyon Ralph and Ida Chau 1993-2014. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of thousands of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
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