Road Cut Mineral Occurrences of St. Lawrence County, New York:

Part I: Beaman Road Barite Occurrence

 

by Michael Walter and Steve Chamberlain

 

This mineral specimen from the Jay Walter is on of the best barites to be produced at the Beaman Road site near Gouverneur, New York. Here is a super cluster of barite, quartz and calcite. 

              Barite and Calcite                                   Barite on Calcite                                                   Barite                                                                      Calcite

 

 

St. Lawrence County in northern New York State is well known for its many mineral collecting localities. Some of these are mines, such as the Rossie lead mines (Robinson et al. 2001) and the Zinc Corporation of America mines at Talcville, Pierrepont, and Balmat (Chamberlain 1996), but most are small, isolated exposures that have only been exploited for mineral specimens. One interesting category of occurrences, which has been underreported in the literature, is made up of road cuts. Frequently, where highways cut through the uneven topography of the Precambrian crystalline rocks of the county, well-crystallized minerals of interest to collectors are encountered. Although the occurrences may be ephemeral, lasting only a few days to a few weeks, the fine mineral specimens they produce are not. Some of the road-cut localities, however, have remained intermittently productive for mineral collecting for decades. With this article we inaugurate a series of reports on road-cut occurrences in St. Lawrence County.

The Beaman Road barite occurrence is exposed in a small road cut on the north side of Beaman Road in the Town of Gouverneur (fig. 4). The road cut is 1.4 kilometers west of the intersection with Peabody Road and appears on the upper left corner of the Gouverneur quadrangle in the U.S. Geological Survey's 7.5-minute topographic series (1956). Although many occurrences in St. Lawrence County have produced barite specimens, those from the occurrence on Beaman Road are among the finest yet found.

History

This locality was rediscovered by the late Angus "Gus" McPherson of Gouverneur, New York, after he read an unpublished manuscript by C. D. Nims, a nineteenth-century mineral dealer from Philadelphia, New York. McPherson's initial collecting efforts yielded calcite specimens, many of which had disfiguring overgrowths of secondary calcite, and a few barite crystals to 1.3 cm in size. With the assistance of Michael Hawkins of the New York State Museum, McPherson was able to obtain the cooperation of both the county and state to permit collecting very close to a secondary road. Construction cones and warning tape were used to indicate the roadside hazard to motorists.

McPherson shared information about this locality with Jay Walter and one of us (MW) in August 2000, and on 15 August, both visited the locality with McPherson and found enough indication of barite mineralization to merit further collecting. McPherson lost interest in the site after the first day of joint collecting, and Walter continued to work the locality for a total of seven days. Only a few local collectors stopped to collect briefly during this period.

During this week of intense collecting, two distinctly different occurrences were encountered. The first was a large pocket with barite, calcite, dolomite, and secondary calcite overgrowths. The second was a fracture-filled seam that produced barite, quartz, and calcite.

The large pocket was encountered on the second day of digging. A small vein of barite led to a series of small (to 10-cm) pockets with calcite crystals, small clusters of bladed barite to 1 cm, and occasional clusters of dolomite crystals; no quartz was found. Some of the calcite crystals showed an iridescent surface, but most were covered by secondary crusts of calcite. By midmorning, however, a large clay-filled pocket was encountered less than 1 meter from the pavement. It measured 2 x 1 x 0.5 meters and took the remainder of the day to excavate. It contained calcite scalenohedra to 20 cm long that were coated with tabular colorless barite crystals to 1 cm across. Some plates of calcite crystals remained attached to the wall; others were already loose in the clay. Except for the presence of barite, these calcite crystals were similar in appearance and occurrence to those from the pockets at the Yellow Lake road cut and the Oxbow road cut several miles to the southwest.

The third day of digging marked the discovery of a solid seam of massive white barite and calcite that snaked less than 1 meter below the soil surface parallel to the road and dipped to the northwest at about 45 degrees. Along this seam were occasional pockets from 0.1 to 0.5 meter across, lined with calcite rhombohedra. Barite, dolomite, and quartz crystals were scattered on the surfaces of the calcite. In the largest pockets, pale blue barite crystals formed coatings to 1 cm thick on the calcite crystals. These overgrowths of barite sometimes broke free from the calcite, leaving calcite-crystal impressions on the backside. The best specimens occurred in a large complex of intergrown pockets approximately 1 meter in length. After this pod was removed, the seam pinched off in all directions. Two more days of digging exposed no more barite seams or pockets of consequence, and digging stopped at the boundaries formed by the pavement and the adjacent private property.

Some of the newly collected specimens were displayed at the Pierrepont Show at the end of the month, and several other collectors subsequently visited the locality, including one of us (SCC). There are no known photographs of the locality during the week of productive collecting; however, figure 3 shows the locality as it appeared in fall 2003.

Geology

The Beaman Road barite occurrence is fracture-filling mineralization in the Precambrian marble (Isachsen and Fisher 1970). The age of the crystallized minerals in the fractures is unknown, but it is certainly much younger than the host rock.

Minerals

Barite, BaS[O.sub.4], occurs as colorless, white, gray, and pale blue tabular crystals to 5 cm long and 1.5 cm thick. The crystals range from nearly opaque through translucent to transparent. Crystals from the barite/calcite seam are generally white to pale blue with a simple combination of the basal pinacoid {001} and the prism {110}. Often the basal pinacoid is stepped, and sometimes the prism faces show bulged, divergent growth. Crystals from the large pocket are commonly colorless to white, and many show a combination of {001}, {110}, and a second prism {102}. Many crystals have only the slightest attachment to their matrix. A few show phantoms caused by variations in transparency during growth. The best specimens came from the barite/calcite seam. Although few in number, these 5-10-cm pieces are dominated by barite crystals 3 cm across associated with calcite, quartz, and dolomite.

Calcite, CaC[O.sub.3], occurs as colorless to white twinned (on {0001}) and untwinned {2131} * scalenohedra to 20 cm in largest dimension. Some crystals are modified by the rhombohedron {1011}. Clusters to 33 cm across were recovered, although the larger specimens are not particularly attractive. Parallel growth is common. Some of the calcite crystals show secondary dissolution from the action of ground water.

Dolomite, CaMg[(C[O.sub.3]).sub.2], forms tan-colored, dull rhombohedral crystals to 1 cm. They occur attached to calcite, sometimes as an epitactic overgrowth; with other minerals; and as loose crystal clusters.

Goethite, FeO(OH), occurs as a thin surface coating on calcite, barite, and quartz crystals and as a replacement of pyrite.

Pyrite, Fe[S.sub.2], occurs as crystalline masses to less than 1 cm across, mostly altered to goethite.

Quartz, Si[O.sub.2], occurs as small, transparent to translucent, prismatic crystals to several millimeters in length. Generally the positive and negative rhombohedral terminations are equally developed.

Paragenesis

Calcite always appears to be the first mineral to have crystallized. Toward the end of the first stage of calcite deposition, there was concurrent crystallization of quartz. The crystallization of barite followed the calcite and quartz. Dolomite and pyrite followed the barite. The last stage in the paragenesis included the alteration of pyrite to goethite, the dissolution of some of the earlier calcite, and the recrystallization on the surfaces of the other minerals as late-stage microstalactitic coatings.

Origin

This occurrence is clearly fracture-filling mineralization that occurred much later than the formation of the host marble. Gash veins and fracture fillings are common in the immediate area; examples include the Oxbow road cut and the Yellow Lake road cut (Robinson and Alverson 1971) and the White farm (loc. 24), MacDonald farm (loc. 73), and Mayhew farm (loc. 41) (Brown 1983). The source of the calcite and dolomite is almost certainly from solution and redeposition of the host rock itself, although whether by descending ground waters (supergene) or upwelling solutions (hypogene) is not clear. The presence of quartz in many of these occurrences could suggest deposition from descending ground waters that carried the silica in solution by means of organic complexes (Bennett and Siegel 1987; Chamberlain 1988) after it was released from the breakdown of metamorphic silicates in the overlying marble. The presence of barite, however, is more problematical. Under surface conditions, barite is chemically stable and bacterial sulfate reduction is generally an anaerobic process. The abundance of barite in this occurrence might suggest a low-temperature hydrothermal origin for the fracture-filling mineralization (as advocated by Brown 1983). Studies of primary fluid inclusions might indicate whether the temperature of formation was consistent with descending ground waters or upwelling hydrothermal solutions. Whatever its source, barite is certainly widespread in the immediate area. It is sometimes an accessory mineral in the open-cavity hematite deposits of St. Lawrence County; (examples include the Caledonia mine near Spragueville (Beck 1842; Robinson and Alverson 1971), the Toothaker Creek prospect on Cooper Hill (personal observations), and the Chub Lake mine near Hailesboro (Beck 1942; personal observations). Barite has also been reported from the zinc mines at Balmat and Edwards (Jensen 1978), and it is a relatively common mineral in fracture-filling veins; examples include the classic locality in the Town of Dekalb (Beck 1942; Jensen 1978), the quartz-calcite-barite vein on the shore of Laidlaw Lake (Beck 1842), the barite veins near Osborne Lake (Brown 1978, loc. 61), the seams filled with crested barite and sulfides on the MacDonald Farm near Gouverneur (Brown 1978, loc. 73), and numerous small road-cut occurrences near Gouverneur (Beck 1842; Edwards, pers. com., 1987).

Accessibility

This site is now closed to collectors. During the period of mineral recovery in August 2000, Angus McPherson and Michael Walter had permission from the county Department of Transportation (D.O.T.) to put up road cones, rope off the site, and excavate. In spring 2001, D.O.T. reclaimed the shoulder area by filling and grading the excavated areas. Although additional mineralization may extend beyond the county right-of-way, the current owners of the adjacent private property have emphatically refused access for further collecting. We suggest that collectors refrain from making new excavations at this time.

ACKNOWLEDGMENTS

We are indebted to the late Angus McPherson for bringing this site to our attention. Without his initiative, the location and its minerals would likely have remained uninvestigated. We also thank Michael Hawkins of the New York State Museum for assistance in obtaining permission to collect on the D.O.T. right-of-way. We thank Dr. John Rakovan for reviewing the manuscript and offering helpful suggestions. This is a publication of the Center for Mineralogy, New York State Museum.

REFERENCES

Beck, L. C. 1842. Mineralogy of New York. Albany, NY: W. and A. White and J. Visscher.

Bennett, P., and D. I. Siegel. 1987. Increased solubility of quartz in water due to complexing by organic compounds. Nature 326:684-86.

Brown, C. E. 1983. Mineralization, mining, and mineral resources in the Beaver Creek area of the Grenville Lowlands in St. Lawrence County, New York. U.S. Geological Survey professional paper 1279.

Chamberlain, S. C. 1988. On the origin of "Herkimer diamonds." Rocks & Minerals 63:454.

--. 1996. Minerals from the Hyatt mine, Talcville, St. Lawrence County, New York. Rocks & Minerals 71:192.

Dietrich, R. V., and S. C. Chamberlain. 1989. Are cultured pearls mineral? The continuing evolution of the definition of mineral. Rocks & Minerals 64:386-92.

Isachsen, Y. W., and D. W. Fisher. 1970. Geologic map of New York, Adirondack sheet. University of the State of New York, the State Education Department, Geological Survey.

Jensen, D. E. 1978. Minerals of New York State. Rochester, NY: Ward Press.

Robinson, G. W., and S. Alverson. 1971. Minerals of the St. Lawrence Valley. Privately published.

Robinson, G. W., G. R. Dix, S. C. Chamberlain, and C. Hall. 2001. Famous mineral localities: Rossie, New York. Mineralogical Record 32:273-93.

 

MICHAEL WALTER

P.O. Box 137

Nicholville, New York 12965

mwalter9@twcnt.rr.com

 

Michael Walter is an active field collector of the minerals of upstate New York and Canada.

 

Dr. Steven C. Chamberlain, a consulting editor of Rocks & Minerals, is a long, time collector specializing in the minerals of New York State.

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