~ Sweet Home Mine ~
The Sweet Home Mine produces many of the world's best rhodochrosite specimens. It's bright red color and gemmy interior place this mineral among the most desirable of all mineral species. The mine is located about 90 miles southwest of Denver, Colorado, near the small mountain town of Alma. The mine was originally developed for silver in the 1870's. Periodically, throughout the mine's lifetime, nice rhodochrosite specimens were found along with the silver ore.
Throughout its 130-year history, the mine opened and closed many times. The last time the mine was worked for silver ore was in the 1960's. Coincident with this period, mineral collecting was gaining popularity and in 1967, a spectacular rhodochrosite specimen was discovered. Following this famous discovery, collectors would forever know the mine as a producer of world-class rhodochrosite specimens.
In 1991, the mine was leased to Sweet Home Rhodo, Inc and reopened as a specimen mine. The mine's 5000 feet of old underground workings had exposed many rhodochrosite targets. These targets were mined for rhodochrosite using classic underground hardrock mining techniques combined with modern exploration and extraction techniques. Every square meter of the mine was examined and mapped for rhodochrosite potential. During the past 12 years of continuous mining, hundreds of incredible rhodochrosite specimens have been discovered.
The mining method begins with underground drilling. 20 to 30 holes are needed to form a blast pattern. When detonated, a 2 meter by 2 meter opening, 2 meters deep is formed. This pattern is repeated again and again thus forming a tunnel underground.
While tunneling is taking place, careful geological,
geochemical and engineering work is employed to locate rhodochrosite-bearing structures. Once a good rhodochrosite pocket is located, special tools are brought in to extract the rhodochrosite specimens. This step is critical. Hydraulic diamond chainsaws and rock splitters are used to carve around and remove the fragile rhodochrosite specimens. One damaged crystal can ruin a specimen's value.
A crew of 8 people is required to maintain the Sweet Home Mine. Several tons of explosives are used every month to blast tunnels and locate rhodochrosite. Thousands of man-hours of labor are required to locate a single pocket. It is often two years between significant discoveries, so patience is critical. One badly placed blast can ruin a year's worth of work.
Once collected, rhodochrosite specimens are transported to a mineral cleaning and preparation laboratory in Golden, Colorado, where a crew of 3 work on cleaning and preparing the specimens for sale.
~ Sweet Home Mine Minerals ~
BORNITE - Cu5FeS4
Bornite appears to be more prevalent in certain veins of the mine than originally thought. It is a component of a late-stage of mineralization that coats other sulfides. Bornite is probably best known from the Tetrahedrite Drift in an area mined during 1993. The bornite usually forms as isolated and intergrown subhedral, rounded crystals up to 8 mm across that usually range in color from deep blue to black. However, bornite also occurs as a blue to purple or silky bronze iridescent metallic coating upon tetrahedrite/tennantite and sphalerite.
CALCITE - CaCO3
Calcite was relatively unknown from the Sweet Home Mine until pale yellow, intergrown crystals were encountered in the Tetrahedrite Drift in 1992. Typically, calcite does not form in well-defined crystals; rather, the crystals are small, modified and intergrown rhombohedra. The finest examples of calcite from the Sweet Home Mine were discovered during 2000 in a rhodochrosite-filled pocket called the Calcite Pocket. A handful of white to pale yellow, complex, scalenohedral calcite crystals to more than 3 cm in length occurred with and on superb, gemmy red rhodochrosite crystals in the Calcite Pocket.
Chalcopyrite is a common mineral in the veins and occurs as small crystals on many specimens. Perhaps the finest specimens of chalcopyrite from the Sweet Home Mine came from a small vug located above the Rainbow Pocket, the pocket from which the Alma King rhodochrosite was recovered. The small vug yielded sharp, lusterous chalcopyrite crystals up to 1 cm that occurred with other sulfide minerals on a quartz matrix.
Fluorapatite is found sparingly in many veins at the Sweet Home Mine. While crystal sizes are generally quite small ranging from 1 mm to 1 cm in length, fluorapatite is one of the more desirable crystallized species from the mine. Color ranges from a light gray to an attractive pale greenish-blue. Fluorapatite is found directly on rhodochrosite, needle quartz, and other minerals. It commonly occurs as translucent to transparent, doubly terminated crystals. Fluorapatite crystals are intimately associated with white dickite in pockets and may occur as 'floaters' in this clay. The Sweet Home Mine fluorapatite fluoresces an attractive pink color in shortwave ultraviolet light.
Fluorite occurs at the Sweet Home Mine as a gangue mineral throughout the various vein structures. Fluorite appears in many colors, from colorless to yellow, blue, green, purple, and brown. The predominant fluorite crystal shape is the cube truncated by dodecahedron faces. Nearly perfect dodecahedrons, octahedral shaped crystals having stacked cube faces, and cube penetration twins have been found. Most of the fluorite crystals are smaller than 1 cm.
Galena occurs in well-formed cubes and octahedrons, usually less than 1 cm. Typically associated with other sulfides, quartz and rhodochrosite. Historically, the galena was thought to be argentiferous and a significant contributor of the silver production from the mine. Recent analyses (Wenrich, Modreski) indicate that galena is typically not a major silver-bearing species at the Sweet Home. Electron Microprobe results on 31 spots from 5 samples yielded silver content values from <0.01 wt% to 0.44 wt%. The major sources of silver in the Sweet Home Mine are the copper sulfides and silver-copper sulfides: Bornite, Digenite, Spionkopite, Stromeyerite.
While hubnerite has long been known from the Sweet Home Mine, it is seldom occurs as crystals of significant size on mineral specimens recovered from the mine. When hubnerite is found, it typically occurs as dark, lusterous, crystallized blades, less than 3.0 cm in length, associated with needle quartz, sulfide minerals, rhodochrosite, and fluorite. Some very nice hubnerite specimens were recovered from a pocket discovered in late 2001 called the Sulfide Pocket.
Mineral collectors are often captivated by the pyrite crystals from the Sweet Home Mine. Many pyrite crystals exhibit rounded, rather bulging, striated cubic faces and serrated edges. Most of the crystals show octahedral modification on the corners. Not all pyrite from the Sweet Home is distorted or striated. A specimen in the Denver Museum of Nature and Science (DMNH #16841) features a nearly perfect 2-cm cube with mirror smooth faces. Associated species include: quartz, other sulfides, hubnerite, fluorite, and rhodochrosite. Pyrite crystal size is generally less than 2.5 cm. A number of beautiful quartz and pyrite specimens were recovered from the Sulfide Pocket (2001).
Quartz is ubiquitous in the veins and is undoubtedly the major gangue mineral. The quartz may be massive within the veins, but, it usually forms attractive, needle-like, white to transparent crystals less than an inch in length. Quartz crystals frequently form the attractive base upon which other species such as rhodochrosite, fluorite, pyrite have crystallized.
The Sweet Home Mine has long been recognized as the source of the world's finest rhodochrosite crystals. Rhodochrosite specimens from the Sweet Home are treasured pieces in public museums and private mineral collections around the world. Sweet Home Mine rhodochrosite crystals can exhibit a spectacular cherry-red color, can have razor-sharp, lusterous crystal faces, and can be incredibly gemmy.
The cherry red color of rhodochrosite from the Sweet Home Mine is due to the relatively low amount of Iron+Magnesium+Calcium impurities. When calcium, magnesium, and especially iron ions substitute for manganese, a pink color will result. Sweet Home Mine rhodochrosite crystals almost always form as simple rhombohedrons. Individual crystal sizes can range from <1 mm to the unequaled size 'Alma King' rhodochrosite rhombohedron that measures 14 cm x 16.5 cm. Well-crystallized quartz, fluorite, tetrahedrite, apatite and other mineral species associate with Sweet Home Mine rhodochrosite, often forming combination specimens of great beauty and desirability. Sweet Home Mine rhodochrosite can be so gemmy that it can be cut into spectacular faceted gemstones.
SPHALERITE - (Zn,Fe)S
Sphalerite is one of the most abundant species found in the Sweet Home Mine. It is an important massive component in the ore, and commonly also occurs in crystal pockets as small, well-formed black, green, yellow, or red crystals. Associates include: quartz, other sulfides, euhedral fluorite, and rhodochrosite.
TETRAHEDRITE/TENNANTITE - (Cu,Fe,Ag,Zn)12(SbAs)4S13
Excellent tetrahedrite/tennantite specimens are recognized from the Sweet Home Mine. Specimens are attractive, with single euhedral crystals or as intergrown clusters of crystals on sulfide matrix, associated with euhedral rhodochrosite, quartz, fluorite, sphalerite, and hubnerite. Typically the crystal faces are bright and untarnished, often exhibiting a distinctive specular appearance. Crystals are generally 7 mm to 2.5 cm in size, but individual tetrahedrite/tennantite crystals up to 5 cm are known, and fragments of even larger crystals have been seen.
1992 - THE DISCOVERY OF THE 'ALMA KING'
During the 1991 season, a small blast had exposed a nice-looking vein in one side of an old tunnel. The tunnel had to be widened to accommodate the mine's underground machinery. By chance, a crewmember, Graham Sutton, chose to blast the right side of the tunnel, instead of the left; thus exposing the vein.
In 1992, the new vein was mapped, studied and finally chosen as a good target for exploration. Unfortunately, after finding very little during the previous year, both budgets and attitudes were drawing thin. The money was almost gone, and mine closure was being considered. Under this stress, a tunnel was started on the new vein. It contained a large quantity of tetrahedrite crystals and became known as the Tetrahedrite Vein. After several weeks, some small pockets were discovered on this vein leading the crews to believe that they were on to something.
By August, patience paid off. On August 21, at 3:00 p.m. a blast opened up a small hole. Inside, the contents were arrayed in every color of the rainbow as rhodochrosite crystals to 15 cm littered the interior. Within one hour, a 15 cm crystal had been collected. All was caught on videotape by the Denver Museum of Nature and Science as one rhodochrosite treasure after the next was pulled from the pocket.
Several weeks later, the pocket was empty. The 15 cm crystal was repaired onto its pocket matrix and became known as the 'Alma King', the largest complete rhodochrosite in the world. Over a 1000 specimens were ultimately recovered from the 'Rainbow Pocket'.
The pocket saved the mine and all because a miner chose to peel one side of an old mine tunnel instead of the other; a 50/50 decision that lead to the success of the Sweet Home Mine. The 'King' is on permanent display at the Denver Museum of Nature and Science, in Denver, Colorado.
1994 ' THE DISCOVERY OF 'THE DENVER WALL OF RHODOCHROSITE'
During 1994, the mine was again suffering through the 'famine' cycle of it's 'feast and famine' lifestyle. The 1992 discoveries were a distant memory and cash was again tight after having a very bad 1993 season.
By September, it had been two years between significant rhodochrosite discoveries. A tunnel was being driven on the southwest extension of the Tetrahedrite Vein several hundred feet from the 'Alma King' discovery. The tunnel was in a favorable-looking area but had only yielded up low-value pyrite crystals for a distance of 50 feet; decisions had to be made whether to continue the work, or halt it. Finally, a decision was reached to shut off all work. The mine geologist, Dean Misantoni, made a case for continuing tunnel work and after much arguing and hand-wringing, the tunneling was again underway. After the very next blast, Dean was tapping the tunnel ceiling with his rock hammer when, suddenly, 'whoosh', a gash opened up above his head and rhodochrosite crystals cascaded down. Rhodochrosite crystals to 7 cm fell into his face cutting into his nose.
The pocket eventually opened into a crack 2.5 meters in diameter and between 6 and 16 cm wide. Thousands of pieces were taken from the pocket after 6 solid weeks of collecting.
The contents were spectacular and after a visit to see William Coors, it was decided to recreate this amazing pocket and place it inside the Coors Mineral Hall at the Denver Museum of Nature and Science.
Today, visitors can view the 'Denver Wall of Rhodochrosite' on a tour of the mineral hall. It contains over 3000 rhodochrosite specimens, measures almost 3 meters across and represents the largest rhodochrosite pocket ever discovered at the Sweet Home Mine.
We have the beautiful cherry-red Sweet Home Mine RHODOCHROSITE cut by skilled U.S. gem cutters into
faceted stones with incredible color and brilliance. These gemstones look stunning in pendants and earrings! The rhodochrosite can also be fashioned into cabochons, tongues, rhombs, eggs, and a variety of other polished forms suitable for use in jewelry and perfect for rare gemstone collections.
If you are interested in more information about rhodochrosite gemstones, please contact our gemstone marketing representative ' Paul Cory of ITECO, Inc. at 614-785-0450 or visit ITECO's website at www.itecoinc.com.