Consequences of Historical Mining

Photograph of a stamp mill and tailings.

Toxic Tailings

Historical gold mining often profoundly impacted the surrounding ecosystem, leaving behind a toxic legacy. People were not always aware of the impact of specific mining practices on the environment or human health.

Mines created waste rock piles and tailings. Waste rock included all of the rock removed in the process of getting to the gold-bearing ore. Tailings were what remained after the gold-bearing ore was crushed into sand-sized particles in a stamp mill and treated with mercury or cyanide to remove the gold. The tailings were dumped into nearby lakes, streams, or other natural depressions. It is estimated that 3 million tonnes of tailings were generated in Nova Scotia’s gold districts between the 1860’s and the 1940’s.

Children playing with toy cars in tailings sand.

Children playing on tailings in Goldenville.

Photo by Dr. Michael B. Parsons, Geological Survey of Canada (Atlantic).

Prior to a scientific study that revealed the tailings at Goldenville have dangerously high concentrations of arsenic and mercury, community members used the tailings area as a place of recreation for events such as 4x4 rallies.

An aerial view of Montague Gold Mines detailing the amount of arsenic naturally occurring in that area.

This aerial view of Montague (near Dartmouth) shows the “halo” of arsenic that occurs naturally in the soils within and surrounding our old gold districts.


The gold-bearing rocks in Nova Scotia contain naturally high amounts of a mineral called arsenopyrite, which bears arsenic. Any activity that disturbs arsenopyrite-bearing rocks could result in releasing more arsenic into the environment. The production of waste rock piles and tailings only served to further concentrate the already abundant arsenic. Arsenic can cause digestive issues, cancer, brain damage and death in humans and is readily absorbed by fish, shell fish, plants and other wildlife.

Photograph of two mason jars containing tailing samples from Nova Scotia.

Tailings from Montague Gold Mines, NS.

Photograph by Steve Farmer Photography.

These tailings are from Montague Gold Mines and were collected in 2009.The tailings contain 20,340 parts per million of arsenic and 2.3 parts per million of mercury. The arsenic content of the tailings is 1,695 times more than the Canadian Council of Ministers of the Environment’s allowable guideline.

The Canadian Council of Ministers of the Environment has set the allowable guideline of arsenic in soils to be 12 parts per million and 6.6 parts per million for mercury.


Mercury was used in the processing of the gold ore; the tailings also have very high levels of mercury. It is estimated that about 10-25% of all mercury used was lost in tailings.

Mercury is consumed by wildlife, such as fish and shellfish, and can cause slower growth rates, reduced fertility or even death. Humans may consume wildlife with high concentrations of mercury, causing similar health issues.


Cyanide was also used to extract gold in historical mining. If cyanide leaks into the environment, its impact is immediate and lethal to people and wildlife. Cyanide does degrade over time, unlike arsenic and mercury, and despite testing, none has been found in the tailings in Nova Scotia.

Abandoned Mine Openings

Black and white photograph of an abandoned mine shaft.

This is an abandoned shaft from the Skerry mine workings at Montague Gold Mines, near Dartmouth.

Nova Scotia Department of Natural Resources Photo Collection

Historical mining activity in Nova Scotia has left a large number of abandoned mine sites which may have unsecured open holes and tunnels – an obvious hazard to people. Dangers can include falling into deep holes, drowning in flooded shafts, and encounters with hazardous chemicals. Nova Scotia has implemented a program to identify and secure such sites.

A Home for Bats

Abandoned mine opening.

An abandoned mine opening before a ‘bat cage’ was installed by the Nova Scotia Department of Natural Resources.

Nova Scotia Department of Natural Resources Photo Collection

The same abandoned mine opening with a grill installed over the opening.

The same abandoned mine with the entranced blocked to let bats in and keep humans out. This makes the space safe for bat hibernation.

Nova Scotia Department of Natural Resources Photo Collection

Abandoned mine shafts provide an important habitat for Nova Scotia’s bats during winter hibernation. Bats need very specific environmental and climatic conditions, and need to be in a place where they are undisturbed during the winter. Why do abandoned mine shafts make for perfect winter hibernation sites for bats?

For winter hibernation, bats require

  • 100% relative humidity
  • areas that do not flood
  • areas with no wind or air movement
  • baffling from outside, so that if there is a temperature change it is gradual
  • complexity of habitat - so they can select, at any given time, spots that meet their immediate roosting requirements; and
  • protection from predation (including people) - that is why total darkness is best

Three species - Little Brown Bats, Northern Long-eared Bats, and Eastern Pipistrelles - all have been observed and recorded at old mine sites. People are urged to stay away from these abandoned mines for their own safety as well as for the health of Nova Scotia’s bat population.

Hazards of Abandoned Mines

Headline from the Chronicle Herald, 'Child Drowns in Well'

“Child Drowns In Well”, The Chronicle-Herald, Halifax, Wednesday, 3 July 1963, p.11.

Nova Scotia Archives Newspaper Collection

Headstone of Russell Herman McGrath

Russell Herman McGrath’s headstone.

Nova Scotia Department of Natural Resources Photo Collection

Russell Herman McGrath drowned in a flooded abandoned mine opening in Wine Harbour when he was just 21 months old. Russell had been visiting his grandmother when he fell into the unprotected shaft, which was only steps away from the house.

Photograph of an abandoned mine shaft showing the water at the bottom.

The abandoned, flooded mine opening in Wine Harbour where Russell Herman McGrath drowned in July 1963. The marks on the photograph were made by the incident investigator.

DNR: Registry file #71680-30-DA.63

Olive MacLeod was one citizen who wrote to her MLA Alex MacIssac in August 1963 urging him to take action to secure the numerous abandoned mine openings before tragedy strikes again. The Nova Scotia Department of Natural Resources has an active program to identify and secure such abandoned mine openings to prevent further accidents.