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Sweet Home Mine (Home Sweet Home Mine), Mount Bross, Alma District, Park Co., Colorado, USA

This page kindly sponsored by Mineral Classics
 
 
A former Ag mine located SW of Mt Bross. Started 1895.

Famous for superb and large rhodochrosite crystals.

Mine Information:
Originally a silver claim prospected in 1873, the underground mine was worked only sporadically and finally abandoned as a silver venture in 1966, after producing a total of $215,000 in then-current silver prices. However, with the discovery of the "Alma Queen" in 1966, development continued, albeit as a series of "poor boy" operations without applying geologic and mining principals to the efforts.

In 1991, the mine property was purchased and, using venture capital, the mine was modernized. Rail was removed, the main adit widened to accomodate LHD haulage, a ventilation system installed, a new portal reestablished, and the dump relocated. The mine was also mapped, sampled, and analyzed.

There is some question as to the details of how mining was approached. One story is that the basic approach, refined over time, was to use drill+blast, and after each round run ground penetrating radar (GPR). If a vug was detected, a hole was drilled, and a fiberoptic camera inserted to examine the contents. It was then a matter of using pre-splitting, expansive agents, or hydraulic chainsaws, whatever would minimize vibrations that would shatter the crystals. Another source omitted the use of GPR, and reported that the fiberoptic camera had too narrow a field of view to be useful and so exploration of vugs depended on the 'jump' felt when the drill bit entered the vug. Then, the drill hole was widened, and futher exposure limited to hydraulic splitters for large vugs, and a diamond chainsaw for smaller ones.

Geology:
Mineralization is generally in base metal-silver-rhodochrosite-fluorite veins predominately hosted by metaigneous and metamorphic rocks, with minor mineralization in porphyritic dikes and pegmatites. There are five main veins in descending order of production: the Main, Tetrahedrite, Watercourse, Blaine and Blue Mud veins. The Blue Mud Vein is a barren post-mineralization fault-vein, and production from the Blaine Vein was minor. Overall, the planned extent of the mine is small (1000 feet x 400 feet) with about 5,000 feet of workings, and the overall hydrothermal alteration zone small, despite evidence of on-strike continuation of the veins in the collapsed Tanner Boy workings directly across Buckskin Gulch. And even within a vein, rhodochrosite finds were limited.

Three conditions were responsible for the formation of vugs: (1) changes in strike and dip of veins, (2) vein intersections, and (3) openings formed by fault bends controlled by host rock foliation. In general, the 2nd condition was responsible for major pockets, and the 3rd for most smaller pockets. Exploration focused on fault/vein intersections. Fluid inclusion studies suggest that the hotest fluid flow produced the gemmiest ruby-red rhodochrosites.

The veins strike predominantly SW at steep dips and unfortunately, several years of unprofitable, barren, upward raise development was undertaken before concluding that the upper limit to gemmy rhodochrosite deposition happened to occur at the adit level of the Main vein. This experience discouraged pursuing even more expensive development of the vein below the adit level. Similarly, lateral development such as advancing to the next known vein, inferred from outcrops, would have been expensive and risky, as would have reopening the old Tanner Boy workings--interpreted as location of cooler fluid flow.

In the 13 years of operation, an estimated 90% of vugs encountered were barren, and there were only 5 vugs that could be considered highly profitable finds; for many years the mine operated at a break-even or loss.

For more information narrated in diary format, excellent graphics, and specimen photos, see the Mineralogical Record, Vol. 20, No. 4.

Mineral List



60 entries listed. 53 valid minerals.

The above list 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

Dana, E.S. (1892) System of Mineralogy, 6th. Edition, New York: 1090.

Pearl (1958), Colorado Gem Trails & Mineral Guide.

Kosnar, R. A. (1979), "Famous mineral localities: the Home Sweet Home Mine." Mineralogical Record: 10(6): 333-338.

Rocks & Minerals (1982): 57: 61.

Rocks & Minerals (1986): 61: 7 & 9.

Rocks & Minerals (1988): 63: 56.

Cobban, R., Collins, D., Foord, E., Kile, D., Modreski, P., and Murphy, J. (1997), "Minerals of Colorado, updated & revised", 665p.

Murphy, J. A. and Hurlbut, J.F. (1998). "Mineralogy: Sweet Home Mine." Mineralogical Record: 29(4): 115-122.

Jensen, M. (2004), A mystery mineral occurrence at the Sweet Home mine, Park County, Colorado: Mineral News: 20(5): 1-2.

Bartos, P.J., Nelson, E.P., and Misantoni, D. (2007), The Sweet Home rhodochrosite specimen mine, Alma District, Central Colorado: the porphyry molybdenum–fluorine connection. Mineralium Deposita: 42: 235-250.

Mineralium Deposita 44 (2009), 415-434.

Update on rare minerals at the Sweet Home mine, Park County, Colorado, Mineral News (2004): 20(9): 1, 3, 10, 11.

Mining Engineer, August 2007

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