M u s e u m  C r e a t e d  L e s s o n

Gold & Technology

ArtGalNS

Art Gallery of Nova Scotia, Halifax, Nova Scotia

Introduction

The first prospectors typically looked for gold along stream beds and shorelines, using water and a simple gold pan to separate flakes or small nuggets of gold from the surrounding pebbles and grit. Rock and sand from the stream bed or shoreline beaches were put in the pan with a small amount of water and swirled around and shaken. Since gold is six times heavier than most other types of rock, the tiny pieces of gold would sink to the bottom of the pan, and the lighter material would be gently washed over the sides. The miners were using gravity to separate the gold from the sands and gravel. This method was very time-consuming and usually yielded only very small amounts of gold.

To speed things up and to increase their chances of finding gold, miners started to use shovels, picks, crowbars, and hammers to dig up and crush quartz. They built sluice boxes, cradles or rocker boxes that allowed them to process larger quantities of crushed rock. Water was poured in to wash away the sand and pebbles. The heavier gold would fall to the bottom of the instrument and catch in specially designed riffles and ridges.

These methods were used for placer mining, which extracted gold that was on or near the Earth’s surface. With advances in mining technology, there were new ways to search for gold deeper underground. Much of Nova Scotia’s gold is in deep quartz veins. When a vein was found, miners would dig a tunnel or shaft down into the earth that followed the direction of the vein in the rock. Blasting and digging mine shafts was also slow and labourious work, but the potential returns were much higher.

In smaller mines, the heavy work was usually done by hand. Buckets, carts, pulleys, and wheelbarrows were used to move the quartz to the surface. Sometimes horses or oxen were used to pull winches or turn huge stone wheels to carry the ore to the surface or crush rock. Eventually, more efficient crushers and stamp mills were developed that mechanized the process of crushing quartz. These mills were powered by water or steam. Steam engines also ran pumps that drained large quantities of water from deep mine shafts.

Once the quartz ore was crushed to sand-sized particles, chemical processes were used to extract the particles of gold. In the stamp mill, mercury was added to the crushed ore as it acts to “catch” the gold as it moved through a series of sloped sluices. This is known as the mercury amalgam gold extraction method. Every week or two the mills were shut down so that the amalgam of gold and mercury could be removed. This amalgam then had to be further processed to separate the two metals. It was poured into a large cotton cloth or chamois leather bag, which was gathered at the top and twisted to squeeze out most of the mercury. The remaining amalgam then had to be heated to evaporate the rest of the mercury, leaving behind the gold. The mercury vapor was captured and condensed back into liquid mercury. The liquid mercury was used again in the stamp mill.

Eventually, cyanidization replaced amalgamation as a way to extract gold. A mixture of lime and cyanide was used to dissolve the crushed quartz, and then the ore was filtered. Zinc had to be added to the remaining liquid to allow the gold to separate and settle. Variations of this method are still the most widely used in gold mining. Cyanide is much more effective than mercury at “catching” the gold.

Today, as well, there are still individual prospectors staking claims and panning for gold in Nova Scotia, using a combination of muscle power, old technology, and new, idiosyncratic inventions to find and separate gold from quartz. There are also several large mining companies in the process of exploration in the province; all mining companies today use a combination of mechanical and chemical processes to separate gold from the surrounding rock.
  
Art Gallery of Nova Scotia, Dian Day, Susan Sellers, Rita Wilson
1860 - 2013
Nova Scotia, CANADA

© 2013, Art Gallery of Nova Scotia. All Rights Reserved.
Learning Object Collection: Gold in Nova Scotia
Learning Object: Mining Technology
Institution: Art Gallery of Nova Scotia