Success at Nickel Plate and Hedley revives skarn interest (March 07, 1988)

Skarn-type deposits have been minor but steady producers of gold throughout history. More than one million kilograms of gold have been produced from 50 skarn deposits worldwide. This represents only those deposits which have been clearly identified as skarns and probably does not reflect orebodies where skarn is considered a minor alternation event.

Garnet and diopside are two of the more common skarn minerals. They occur with lesser amphibole and epidote in a wide variety of geologic environments that are often associated with other ore- forming processes. For example, many porphyry copper deposits have associated skarn mineralization in carbonate host rocks peripheral to the intrusion. Lead/zinc/silver veins in limestone can often be traced back toward higher-temperature skarn minerals. In several instances, previously mined North American deposits can now be best explained as skarns. However, the spotty nature of mineralization and apparently erratic gold assays often associated with skarns have not made them an attractive exploration target in the past. Interest revived

With the recent redevelopment of the Nickel Plate mine, near Hedley, B.C., development of the Fortitude and McCoy mines, near Battle Mountain, Nev., and the Red Dome mine in northeastern Queensland, Australia, interest in skarns has revived. Several mining companies are now actively exploring specifically for gold skarns in southern British Columbia and the northwestern U.S. A focused exploration program for these deposits is now possible, based on what we know about skarns, the regional geology of British Columbia, and the categorization of known skarn deposits in minfile.

Several ongoing studies of gold in skarn deposits illustrate the combined importance of favorable host rocks and sufficient ground preparation as prerequisites for formation of these deposits. Thinly bedded sequences of impure carbonates, volcanic flows, volcaniclastics and argillites that have not undergone significant metamorphism are common hosts. Good permeability, in the form of pre-mineralization faults, lithologic contacts and hydrofracturing of the country rock during cooling of intrusions, is imperative to allow large volumes of hydrothermal fluid to flow through the system. MDA study

A study funded by mda, the Mineral Development Agreement between the governments of Canada and British Columbia, and led by Art Ettlinger, is looking at the geochemistry of plutons associated with several gold-enriched skarns in the province. Equally important is the study of alteration halos associated with these deposits. Reflected light ore microscopy, whole-rock X-ray fluorescence, electron microprobe analyses and fluid inclusion studies are all being utilized in a combined approach to fully describe the genesis and characteristics of skarns.

An interesting sidelight to this study is a minfile compilation by Art Ettlinger and Gerry Ray of all gold-enriched skarn deposits in British Columbia. It is published as an Open File Map and was presented at the Cordilleran Roundup in Vancouver in February, 1988.

This open file consists of a map showing the location of each known deposit, ranging from occurrences to established gold producers, and a table of geologic information and production/assay data, where available, for each deposit. To date, more than 150 gold-enriched skarn locations have been identified in the province.

Large areas of favorable strata for gold-skarn development are found in British Columbia. This fact, along with the province’s tectonic and plutonic history, virtually ensures that as more interest is shown in skarn deposits, more mines will be found. Reprinted from the Canada/British Columbia Mineral Development Agreement Report, Vol. 2, No. 1, January, 1988.

Skarn-type deposits have been minor but steady producers of gold throughout history. More than 1 million kilograms of gold have been produced from 50 skarn deposits worldwide. This represents only those deposits which have been clearly identified as skarns and probably does not reflect orebodies where skarn is considered a minor alternation event.

Several on-going studies of gold in skarn deposits illustrate the combined importance of favourable host rocks and sufficient ground preparation as prerequisites for formation of these deposits. Thinly bedded sequences of impure carbonates, volcanic flows, volcaniclastics and argillites that have not undergone significant metamorphism are common hosts. Good permeability, in the form of pre- mineralization faults, lithologic contacts, and hydrofracturing of the country rock during cooling of intrusions, is imperative to allow large volumes of hydrothermal fluid to flow through the system. mda study A study funded by mda, the Mineral Development Agreement between the governments of Canada and B.C., and led by Art Ettlinger, is looking at the geochemistry of plutons associated with several gold- enriched skarns in the province. Equally important is the study of alteration halos associated with these deposits. Reflected light ore microscopy, whole-rock X-ray fluorescence, electron microprobe analyses and fluid inclusion studies are all being utilized in a combined approach to fully describe the genesis and characteristics of skarns.

An interesting sidelight to this study is a minfile compilation by Art Ettlinger and Gerry Ray of all gold-enriched skarn deposits in B.C. It is published as an Open File Map and was presented at the Cordilleran Roundup in Vancouver in February 1988.

This open file consists of a map showing the location of each known deposit, ranging from occurrences to established gold producers, and a table of geologic information and production/assay data, where available, for each deposit. To date, over 150 gold-enriched skarn locations have been identified in the province.

Large areas of favourable strata for gold-skarn development are found in B.C. This fact, along with the province’s tectonic and plutonic history, assure that as more interest is shown in skarn deposits, more mines will be found.