Freeport Tunnel

Creede, Colorado

37.8714°N 106.9345°W

Mine Overview

The Freeport Tunnel is near Creede, Colorado. Historically the site has been associated with the Creed Mining District which is now part of the Rio Grande National Forest. The site was first discovered in 1919 by Fred Monkemeyer. Mine operations consist of underground workings. There is one known shaft. Subsurface length extends a maximum of 207 meters (680 feet). The ore mined is composed of acanthite with waste material consisting primarily of limonite, hematite and barite. Associated rock in this area is quartz latite from the Oligocene epoch 33.90 to 23.03 million years ago. The Southern Rocky Mountains physiographic province of the Rocky Mountain System characterize the geomorphology of the surrounding area.

Site identification and general characteristics. Learn about USGS mines.

Silver Primary Commodity
Site Record Type^?
Prospect Development Status^?
1919 Year Discovered^?
Ore Mineral In Place Discovery Method^?
Fred Monkemeyer Discovered By^?
Metallic Site Commodity Type^?
Small Mine Size^?

Mine Names

Name^? Status^?
Freeport Tunnel Current

Owner Name and Address

Homestake Mining Company

Grand Junction, Colorado

Type: Owner

Minerals Engineering Company (Meco)

Grand Junction, Colorado

Type: Owner-Operator

Commodities

Additional textual information about a site or mine.

Commodity Type Importance
Silver Metallic Primary

Deposit

SILVER SULFIDES WITH TRACE OF BASE METALS ARE VERY FINELY DISSEMINATED IN 1) CARBONACEOUS, TUFFACEOUS, SILTY TO COARSE-GRAINED SANDSTONE IN LOWER MONKEMEYER SS ., AND 2) IN SANDY MATRIX OF COMMODORE CONGLOMERATE AND ASSOCIATED WITH IRON AND MANGANESE OXIDE ALTERATION OCCURRING AS FRACTURE AND PORE SPACE COATINGS. MINERALIZATION FOUND BOTH IN SILICIFIED AND NONSILICIFIED ROCK.

Location Info

Mineral , Colorado County / State

Continent Country State County
North America The United States Colorado Mineral

Notes

S-T-R, LAT-LONG, AND ELEV DETERMINED FROM EMMONS AND LARSEN'S (1923) TOPO MAP (1:24, 000 ). MINE OR CLAIM LIES ON SE SIDE OF BACHELOR MOUNTAIN SOUTHWEST OF BACHELOR AND COMMODORE MINES.; INFO FROM LAND. ST : (1976).

Meridian / Township / Range Description

Meridian^? Township^? Section^? Aliquot^?
New Mexico Meridian T.42N R.1W Sec. 24 NE
New Mexico Meridian T.42N R.1W Sec. 24 SW

Land Status

Land status information.

Land Status^? Admin Area^?
Private -

Mining Districts

Formal or informal mining district names.

District
Creed Mining District

Development

RICH ORES ASSAYING AS HIGH AS 800 OZ/TON SILVER WERE MINED AND QUICKLY DEPLETED FOLLOWING 1919 DISCOVERY. NO PROSPECTING UNTIL 1975 UNDER MECO-FREEPORT JOINT VENTURE; 1981 FEASIBILITY STUDY INDICATES PROVEN AND PROBABLE RESERVES OF 3. 348 MILLION TONS OF ORE AT 6. 39 OZ/TON SILVER. EXPLORATION AND EVALUATION CONTINUING.

Workings

Workings at the site.

Underground Workings #1

Type: Underground
Sub Surface Length: 207.26 Meters

Workings

ONE TUNNEL DRIVEN WESTERLY 680 FEET

Concentration Process

Processes that concentrated or enriched the mineralization of the mine.

Concentration Process
Following Collapse And Resurgence Of Creede Caldera And Dome, High-Energy Streams Cut Steep Valleys Into Bachelor Mtn. And Other Rhyolites And Deposited Coarse Conglomerates In Valleys Trending South Into Creede Caldera Moat. Bachelor Mtn. Paleovalley Trend Was Controlled By Creede Graben. Later Faulting Of Creede Fm. On Amethyst Fault Hanging Wall Suggests That Lower Part Of Creede Sediments Filling The Paleovalley And In Contact With Amethyst Fault Were Penetrated By The North-To-South-Flowing Hydrothermal Convection Cell Whose Sulfate-Rich Solutions Are Thought To Be Responsible For Ore Deposition In The Amethyst And Related Veins. These Solutions Thus Leaked Out Of The Fracture-Controlled Convection System In The Rhyolite And Into The Overlying Porous Conglomerate. However, The Exact Relations And Ore Controls Are Still Uncertain.

Materials

Minerals or other materials present in the mine.

Role^? Material^?
Gangue/Waste Barite
Gangue/Waste Hematite
Gangue/Waste Jarosite
Gangue/Waste Limonite
Ore Acanthite

Rocks

Geological materials at the site.

Class^? 1st Order Name^? 2nd Order Name^? 3rd Order Name^? 4th Order Name^? Most Specific Name^? Begin Time End Time Description^?
Associated Rock Fisher Creek Quartz Latite Volcanic Rock (Aphanitic) Felsic Volcanic Rock Quartz Latite Quartz Latite Oligocene Oligocene -
Host Rock Commodore Conglomerate Member Of Creede Formation; Monkemeyer Sandstone Member Of Creede Formation Sedimentary Rock Clastic Sedimentary Rock Conglomerate Conglomerate - - -
Host Rock Sedimentary Rock Clastic Sedimentary Rock Sandstone - Sandstone - - -
Mineralization - - - - - Miocene Miocene -

Structure

Geologic structural features affecting or characterizing the site or mine.

Scale Description
Local Amethyst Fault, Bachelor Mountain Paleovalley (controlled By Creede Graben)
Regional La Garita, Creede, And Bachelor Calderas; San Juan Volcanic Field

Tectonic

Tectonic setting in which the site or deposit is situated.

Setting^?
Central Cordillera (Southern Rocky Mountains)

Physiography

Physiographic area where the resource is found.

Division Province^? Section
Rocky Mountain System Southern Rocky Mountains -

Alteration

Mineralogical and chemical alteration at or near the site, which may help to indicate the geographic extent of the geological processes producing the mine.

Type^? Alterations
Local Silicification

Analytical Data

Results of chemical or mineralogical analysis on materials at or near the site

Line^? Analysis Data^?
1 G.T. 3 OUNCE PER TON SILVER

Ore Control

Controls on emplacement of ore such as faults or other structural features.

Text^?
Carbonaceous Matter In Sandstone; Porous, Altered, Sandy Matrix In Conglomerate

Nearby Deposits

Other deposits in the same region.

Nearby Places

Creede (1.59 miles away)
Cathedral (16.42 miles away)
South Fork (21.27 miles away)

Nearby Mining Districts

Creed Mining District (0 miles away)
Bondholder Mining District (6.15 miles away)

Nearby Lands

Rio Grande National Forest (0 miles away)
La Garita Wilderness (3.49 miles away)
Gunnison National Forest (5.61 miles away)

Footnotes

* Mine bounds on map indicate the general area that a mine occupies. For an detailed map, refer to the overseeing BLM field office.

** The mine central point is based on an average of the mine's bounding box(es) and does not necessarily fall on the claim itself.

¹ World-class significance is determined by total endowment of the contained commodity. This includes all past production and remaining reserves. Each commodity is considered separately and commodities cannot be combined to arrive at a significant size. The tonnage thresholds are from the mine model grade-tonnage studies. As of June 2008, many entries were classified as significant under less strict rules.

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