160 Year Old Granite Mine EarthCache

Sherbrooke Village History

Sherbrooke is a community on the eastern Shore of Nova Scotia.  It is located along the St. Mary's River, a major river in Nova Scotia. The community is named for Sir John Coape Sherbrooke. Gold was discovered in the area in 1861 and Sherbrooke entered a gold rush which lasted two decades.  During that time many buildings were constructed.  The foundations of houses and public buildings were constructed of granite stones from a quarry near Fifth Lake and several other areas within 10 kms.  The stones were mined, mainly by three Jordan brothers and taken out with horse and cart.  The village of Sherbrooke is now an historic site, part of the Nova Scotia Museums.  The historic Sherbrooke Village is open to visitors for tours during the day in the summer months.  In the off season, the village gates are open to public.

This earthcache will take you to the location near an old quarry and two areas in Sherbrooke Village where you can see the products of the quarry, still in use over 160 years later. 

Granite 

Granite is the best-known igneous rock because it is the most common igneous rock found at Earth's surface and the most abundant rock in the continental crust. Granite is formed by high heat and pressure from molten rock material called magma.  As the magma cools, it solidifies.  Some form below Earth's surface. Some form on or above Earth's surface. These two basic types of igneous rocks are called intrusive or exclusive. Intrusive igneous rocks crystallize below the Earth's surface, and the slow cooling that occurs there allows large crystals to form typically the size of a pea. Extrusive igneous rocks erupt onto the surface, where they cool quickly to form smaller crystals some as small as the head of a pin.

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Granite is composed mostly of feldspar and quartz with trace amounts of micas and amphiboles that are present in crystals large enough to be visible with the unaided eye. The size of the crystals in granite determine how the granite is used.  Monumental granite must be fine grained, with crystals the size of a pinhead, to allow fine carved details and to accept a mirror-like polish.  Building granite is more coarse-grained with large crystals which provide strength.  The color of granite can range from pink to cream, white and grey; and depends on the type of feldspar that predominates. The potassium-rich orthoclase feldspar, has a salmon pink color, while sodium-rich plagioclase feldspar, is white to gray. 

Granite also has a varying amount of other minor minerals, such as the black mica biotite, and the black amphibole hornblende, both of which give granite its classic salt and pepper appearance.

Visual inspection, using a hand lens, one may confirm that the minerals of granite are present in the rock. That inspection would involve confirming that each of the minerals expected in granite is physically present in the rock - and present in the proper proportion.

Here is a summary of what you might observe on a broken surface of granite:

Granite Composition

Feldspar
Granite's principal element is feldspar. In addition to contributing to strength and hardness, feldspar primarily determines granite's color, resistance to discoloration and decay, and ability to receive a polish.  Feldspar minerals are usually white, gray, pink or reddish in color. Many grains will exhibit two directions of cleavage that intersect at right angles. You should be able to observe this cleavage pattern in granite with a hand lens. Feldspar is the name of a large organization of rock-forming silicate minerals that make up over 50% of Earth's crust.

Quartz
Quartz contributes to granite's strength, hardness, and luster, and acts as a cement binding all the elements together.  Quartz will usually be a transparent mineral that is colorless or gray in color.
will usually be a transparent mineral that is colorless or gray in color. Quartz is a hard, crystalline mineral that is the second most abundant mineral in Earth's crust after feldspar.

Mica
Mica (mostly white muscovite and black biotite) is present in smaller amounts. The relative amounts of white and black mica are an important factor in the color of the granite. If white mica predominates, the granite will be light-colored, and if the black predominates, the granite will be dark. If the white and black occur in roughly equal amounts, the granite will be speckled. 

Grante is the rock most often quarried as a "dimension stone" (a natural rock material that will be cut into blocks or slabs of specific length, width, and thickness). Granite is hard enough to resist abrasion, strong enough to bear significant weight, inert enough to resist weathering, and it accepts a brilliant polish. These characteristics make it a very desirable and useful in both interior and exterior applications. Rough-cut and polished granite is used in buildings, bridges, paving, monuments, and many other exterior projects. Indoors, polished granite slabs and tiles are used as countertops, floor tiles, stair treads, building veneer, and cemetery monuments. Granite is also used as a crushed stone or aggregate. In this form it is used as a base material at construction sites, as an aggregate in road construction, railroad ballast, foundations, and anywhere that a crushed stone is useful as fill. 

A large part of Nova Scotia is dominated by granitic rocks, from Wedgeport in the south- east to Cape North at the tip of Cape Breton Island, an over-all distance of about 400 miles, where granite tends to form knolls and upland areas characterized by a hummocky, boulder-strewn surfaces and topped with thin, acid soils. There are extensive areas of exposed bedrock. The age of Nova Scotia granites range from 320-500 million years. Age studies show that granites at nearby Archibald's Lake Guysborough Co, are estimated to have formed about 340 million years ago.

Historically, Granite was commonly used for retaining walls, house foundations, well linings, posts, steps and sills in North America since the 18th century. Splitting rocks was largely the farmer's domain. In the 18th century this was done by drilling a very deep hole into a stone, filling it with black gunpowder and blowing it apart. Alternatively, a fire could be lit on top of a boulder, the heat allowing it to be split more easily with the blows of a mallet. The resulting rubble could be used for fences, wells, house cellars, foundations, chimneys or stone walls.   

The early stoneworker might have used other primitive splitting techniques: Splitting by impact with a dropped iron ball or a large sledge, use of expanding ice in holes or cracks, use of expanding wet wooden wedges in cracks, and grooving and then hammering along the groove. The use of a flat wedge and flat shims in slots made by a cape chisel was a great improvement, providing better control over the direction of the splitting. By the early 19th century, quarrying and quarrying methods had been developed to allow for stone to be split into symmetrical, six-sided blocks for use in foundations, or as steps and posts, etc. 

This site and several quarries in the Sherbrooke area were the source of granite stones used to build foundations for houses, churches and fences in the mid to late 1800s.  Examples of these granite stones can be seen at several locations in Historic Sherbrooke Village.(See waypoints)

To log this Earthcache visit GZ and the viewing locations. 

Please answer the following questions and send in a timely manner to my geocaching profile or email. Answers not received will result in deleted logs.  

1. What is the height and width of the granite outcrop near GZ? Do you see any evidence of rock splitting near GZ?

2. At GZ and viewing location 1,  Using a hand held lens, examine the largest rock at each location.  What is the color/s of the largest granite boulder?  Based on the color/s- is there feldspar, Quartz or Mica present in the granite?  Is it fined grained or coarse grained?

3.  How is the granite used at viewing location 1?  What property of granite makes it suitable for this use?

5. [REQUIRED] In accordance with the updated guidelines from Geocaching Headquarters published in June 2019, photos are now an acceptable logging requirement and WILL BE REQUIRED TO LOG THIS CACHE. Please provide a photo of yourself or a personal item in the picture to prove you visited the sites.