Geology Minerals and Mining in Nova Scotia

Nova Scotia Department of Natural Resources
Mineral Resources Branch
Information Series ME 1, 1976

Table of Contents

• Introduction
• Some Interesting Geological Features to be Seen in Nova Scotia
• Mineral Collecting Localities in Nova Scotia
• Geological History
• Methods of Formation of Some Major Commodities of Nova Scotia
• Gold Production in Nova Scotia
• Coal Production in Nova Scotia (to 1975)
• Nova Scotia Commodity Production Totals by Area
• Total Production of Minerals in Nova Scotia (to 1975)
• General Information
• References

Introduction

This publication was designed to give a very basic account of mining and geology in Nova Scotia. It proved difficult to capsulize and summarize the vast amount of information that we thought should be in a publication of this type. However, it is felt that the information given here will be of use not only to students and people in the earth sciences, but it will be of interest to tourists travelling in Nova Scotia.

The information contained in this pamphlet was derived from various sources, most of which are listed under "References."

It must be noted that there are restrictions on the collecting of mineral and fossil specimens in Nova Scotia. Many areas of the province are held under mineral licenses and it is illegal for outsiders to take minerals from these areas without permission. Information in this regard may be obtained from the Registrar at the Nova Scotia Department of Mines. Information on fossil collecting can be obtained from the Director, Nova Scotia Museum.

The following warning must be adhered to. Extensive care must be taken by anyone exploring or looking at the old mining areas in the province. Many old shafts are open, and deep, and these shafts and tunnels are in varying stages of instability. Also old mining pits, trenches and quarries are considered dangerous because of loose rocks, and water seepage which indicates uncertain depths. The government cannot be held responsible for personal injury or loss.

This pamphlet was compiled by Jean M. Richardson and Diane J. Gregory.

Honourable William Gillis,
Minister

John C. Smith,
Deputy Minister

F. S. Shea, Director,
Mineral Resources and Geological Services

Some Interesting Geological Features to Be Seen in Nova Scotia

Mineral Collecting Localities in Nova Scotia

Map: (Not presently available)
Mineral Collecting Localities in Nova Scotia

Geological History

Precambrian

In Nova Scotia the Precambrian rocks are largely concealed beneath a cover of Paleozoic and younger strata. The largest exposed areas is in the Cape Breton Highlands and another belt is confined to the eastern half of Cape Breton. These ancient rocks consists of a complex of metasediments - folded and faulted schists, gneisses, limestones and dolomites, together with complex igneous intrusions. They have been divided into two separate units known as the George River Group and the Forchu Group respectively.

Paleozoic

Cambrian:

The only area in which rocks of Cambrian age are known is in eastern Cape Breton. The oldest of these rocks are shales, sandstones and conglomerates and lie on Precambrian rocks without any apparent break and pass upward into the fossiliferous Cambrian sediments. The remainder of the Cambrian sequence in Cape Breton is divided into a number of different formations. There are several breaks in the series as indicated by the fossil content. Small stocks of granite invaded the Cambrian rocks during Devonian time and extensive folding occurred.

Ordovician:

Ordovician rocks are sedimentary but have been extensively metamorphosed by volcanic and intrusive magmas and lavas.

Rocks of the Meguma Group (Gold-Bearing Series) are believed to be Ordovician or earlier in age and extend the entire length of the mainland from Yarmouth to Canso. The Meguma Group consists of a great thickness (20,000-35,000 feet) of conformable quartzitic greywacke and slate. The entire group is remarkably lacking in fossils and its age is assessed somewhat doubtfully by the existence of Ordovician fossils in a narrow belt of rocks exposed south of Kentville. This belt is cut off from the main body of Meguma sediments by a granitic intrusion.

The Ordovician Meguma group has been closely folded into anticlines and synclines. In addition, there are some cross-folds, giving rise to a series of domes. The granitic masses that cut them are of Devonian age. Gold occurrences are numerous in the Meguma.

Silurian:

The best section of Silurian strata in Nova Scotia is at Arisaig, Antigonish County, where there are 2½ miles of good exposures of tilted and folded sediments consisting of sandstone, argillaceous sandstone, siltstone, shale and volcanic rock. The basal Silurian beds rest unconformably on Ordovician rhyolites and tuffs. Fossils are plentiful and deposition took place in a relatively shallow sea, the floor of which subsided to accommodate the 4,000 to 5,000 feet of sediments.

Silurian fossils have also been found in shale and sandy shale in the metamorphic complex of the Cobequid Mountains.

Devonian:

Rocks of Lower Devonian age occur in Nova Scotia in the vicinity of Arisaig where over 1,000 feet of red sandy shale and sandstone carry remains of freshwater fish. Sedimentation during the Devonian was accompanied by widespread volcanism, and at the close of the epoch, extensive deformation took place known as the Acadian Orogeny. Devonian intrusive rocks, chiefly granite, occur in a broad irregular belt extending from the extreme west end of the province to Cape Canso and throughout Cape Breton Island.

Carboniferous:

Numerous areas in Nova Scotia are underlain by Carboniferous strata. These strata are the province's source of coal, oil shale, salt, limestone, dolomite, celestite, barite, gypsum and anhydrite. Rocks of the Lower Carboniferous (Mississippian) period are divided into the Horton and Windsor Groups. The Horton Group consists of continental deposits of conglomerate, sandstone and dark shale. Remains of fossil plants and buried forests occur and there are some thin localized coal seams. Fossil fish also occur and provide evidence of brackish lakes.

The Windsor Group consists of marine sediments. These include sandstone, shale, conglomerate, limestone, dolomite, gypsum, anhydrite and salt. Above the basal limestone, most of the limestones are very fossiliferous. It is within the Windsor Group that the majority of industrial minerals are mined. Total thickness of the Windsor Group varies from 1,000 feet to 10,000 feet.

The Upper Carboniferous (Pennsylvanian) rocks in Nova Scotia are continental in origin, and were laid down during a period of crustal unrest resulting in alternate rising and sinking of the land areas. They consist of rather uninteresting red and grey sandstone, conglomerate, siltstone, and shale which contain thin bands of dark carbonaceous and calcareous shale.

The coal deposits of the Pennsylvanian have long been of considerable economic importance. They were formed in the flat areas near the centres of the individual basins where river flood plains encouraged the growth of luxuriant vegetation with a swampy environment. Accumulation of great thickness of vegetable matter could only take place under rather stable conditions and then renewed tectonic activity buried the deposits under floods of sediment. The coals differ in age in the various coal basins.

Following the Carboniferous era, there was a period of erosion caused by folding and a general uplift of the land. This continued for about 55 million years or throughout the Permian era.

Mesozoic

Triassic:

The youngest consolidated rocks in Nova Scotia are of Triassic age. The Annapolis-Cornwallis Valley, and both sides of the Minas Basin, are underlain by the Annapolis Formation of sandstone, shale and conglomerate. A few fossil plants and some reptilian remains have been found. These rocks are capped by about 1,000 feet of amygdaloidal basaltic lava forming the North Mountain Upland. It is in this basalt that amethyst, copper, agate, zeolites and other "trap-rock" minerals are formed.

Cretaceous:

Stratified layers of interbedded clay, quartz sand and lignite, of Early Cretaceous age, exist in the Middle Musquodoboit-Shubenacadie area of Halifax and Hants Counties. These clays and sands are overlying rocks of the Windsor Group and are covered by Pleistocene boulder clay. Economically the clays are kaolinitic, grading from low duty to high duty refractory materials, while the quality of the sands varies from 80 per cent to a high of 98 per cent silica.

Cenozoic

Pleistocene

The final event in the story of the geology of Nova Scotia was the glaciation which deposited a thick mantle of bouldery clay that hides from view most of the bedrock beneath. Other features that indicate the work of the ice are drumlins and eskers. The edge of the ice sheet extended beyond the eastern shoreline of Nova Scotia and the moving ice scoured the rock surface over which it moved, plucking and grinding the rocks beneath it. Such grooved and striated surfaces are often exposed and they show that the ice came primarily from the northwest. The ice withdrew from Nova Scotia only about 8,000 years ago.

Map: (Not presently available)
Generalized Geological Map of Nova Scotia

Methods of Formation of Some Major Commodities of Nova Scotia

Coal

Approximately 300 million years ago during the Pennsylvanian Period swamps existed over areas that are now known for their coal deposits - Springhill, Pictou, western Inverness County and Sydney. As these areas became covered with rock debris from surrounding highlands, the ferns and trees and vegetation were buried. With millions of years of rock piled on top of these swamps, the heat and pressure caused the vegetation to turn into the black carbonaceous substance known as coal. With changes in the land form the rock hard coal was eventually exposed on the surface and man was able to mine coal and use it as a fuel.

Evaporites - Limestone, Gypsum, Salt

The abundance of these rock types exist in Nova Scotia because during the Mississippian period, over 300 million years ago, large areas of land were drying up and producing restricted basins, or arms of the sea that were cut off from regular water circulation. As these basins evaporated the water precipitated out its various chemical components. A sequence of rocks is deposited in this way starting with limestones then gypsum and anhydrite, and finally depositing salt. These sediments were buried and consolidated and eventually exposed to the surface by erosion and other methods of land formation.

Metallic and Non-Metallic Minerals

When melted rock from the centre of the earth, known as magma, pushes to the surface, it will heat the surrounding rocks already present. These rocks can change or metamorphose in many ways due to the heat and pressure caused by the rock moving up. Elements may become rearranged and form new minerals. This changing process is known as metamorphic alteration.

Heated water accompanying the magma can also change the pre-existing country rocks. This water is often rich in elements such as gold, copper, molybdenum etc., as these heavy metals are more concentrated in the centre of the earth than on the surface. When it eventually evaporates, the heavy metals are left behind in hydrothermal deposits.

The outside of the magma body cools more quickly while the inside remains hotter. If this liquid rock "spurts" into a crack in the country rock, it can form a vein or sheet of igneous material such as quartz or granite. This is known as metathermal injection.

The precious native metals such as copper and gold that are found in Nova Scotia are produced by a hydrothermal deposition and metathermal injection. Native metals are usually very pure and wiry of "chunky." Quartz injected into cracks between the bedding planes of folded Ordovician slates had a high percentage of liquid gold from deep in the earth. Cooling hardened the solutions and millions of years later these quartz veins were mined for gold.

Superheated water moving in the iron-rich Triassic lavas of the Bay of Fundy carried high concentrations of copper, silica, and other elements. This water fills "air bubbles" or cavities and native copper, agate, amethyst, zeolites, chalcedony, and other semi-precious minerals are formed.

Hydrothermal alteration is also known as replacement. Water circulating through a deposit or formation may introduce new elements while dissolving and removing existing elements. Gradually the pre-existing rock will change. In many cases the water is laden with sulfur particles which attack and replace the county rock. The minerals barite and celestite are formed in this manner.

Gold Production in Nova Scotia

Coal Production in Nova Scotia (to 1975)

Map: (Not presently available)
Gold Districts and Coal Fields in Nova Scotia

Nova Scotia Commodity Production Totals by Area

Only Production Totals of over 5,000 tons are shown for Industrial Minerals and Construction Materials with the exception of Diatomite (over 1,000 tons) and Stone/Gravel (over 100,00 tons). All known production is given for Metallic Minerals.

Map: (Not presently available)
Present & Past Producing Mines & Quarries in Nova Scotia

Total Production^* of Minerals in Nova Scotia (to 1975)

General Information

The following are addresses of agencies from which more information relating to rocks and minerals in Nova Scotia may be obtained.

Nova Scotia Department of Natural Resources Library
(formerly Department of Mines)
Third Floor, Founders Square
1701 Hollis Street, P. O. Box 698
Halifax, Nova Scotia
B3J 2T9

Telephone: 902-424-8633
FAX: 902-424-7735
nsdnrlib@gov.ns.ca

Geological Survey of Canada
601 Booth Street, Ottawa, Ontario.

Nova Scotia Museum
1747 Summer Street, Halifax, Nova Scotia.

Nova Scotia Mineral and Gem Society
c/o Nova Scotia Museum
1747 Summer Street, Halifax, Nova Scotia.

Attractions of interest regarding mining and geology in Nova Scotia.

Nova Scotia Museum, Halifax
Springhill Minerals Museum (Coal) Mine Tour
Cape Breton Miners Museum (Coal), Glace Bay.
Princess Mine (Coal), Sydney Mines, Mine Tour.
Old French Mine (Coal), Port Morien, Mine Tour.
Stellarton Mining Museum.
Geological, Mining and Gem Museum, Parrsboro.
Colchester Historical Museum, Truro.
Marble Mountain Library and Museum, Inverness County.
Rock and Mineral Collections at Nova Scotia universities.
Annual "Rock Hound Round-up", Parrsboro, in August.

References

Nova Scotia Department of Natural Resources (formerly Department of Mines):

A Brief History of Mining and Geology in Nova Scotia, 1975.
Annual Reports on Mines, 1861-1975.
Mineral and Geological Guidebook, 1954.^*

Geological Survey of Canada:

Rocks and Minerals for the Collector; Bay of Fundy Area, by Ann P. Sabina, Geological Survey of Canada Paper 64-10, 1964.

Rocks and Minerals for the Collector; Northeastern Nova Scotia, Cape Breton and Prince Edward Island, by Ann P. Sabina, Geological Survey of Canada Paper 65-10, 1965.

Rock and Mineral Collecting in Canada, Volume III - New Brunswick, Nova Scotia, Prince Edward Island and Newfoundland, by Ann P. Sabina, Geological Survey of Canada Miscellaneous Report 8, 1965.

Gold Fields of Nova Scotia, by W. Malcolm, Geological Survey of Canada Memoir 385, 1976 (3rd Edition).

Physiography of Nova Scotia by J. W. Goldthwait, Geological Survey of Canada, Memoir 140, 1924.^*

The above publications are a small selection of references and will give more detailed information on rocks and minerals in Nova Scotia. The references marked with an asterisk (^*) are now out of print. but many libraries would have them. The other publications can be obtained from the respective agency as listed.

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