Minerals

There are over 4 000 different types of minerals. All minerals are usually found in a solid state, although they can be in a liquid state if subjected to high temperatures and pressures.

Unlike a rock, a mineral is a pure substance made up of identical elements. It is thus possible to identify minerals since they have specific properties. In addition, a mineral has only one dominant colour, although impurities are often found in samples.

Luster

The luster can be metallic (if it has a highly reflective or shiny surface), sub-metallic (if the surface is slightly reflective), or non-metallic (if the surface is not reflective).

Check a mineral’s luster by placing the sample under a light source and observe the mineral’s reflection.

Colour of the Mineral

To check the colour of the mineral, it is preferable (if possible) to break the mineral to note the observable colours on the breakage.

Transparency and Opacity

The more translucent a mineral, the more light it lets pass through — although objects can appear blurry when looking through the mineral.

To observe the transparency of a mineral, it is necessary to observe an object through a mineral and determine how blurry the observed object is or not.

Refractive Index

Streak Colour

To determine the colour of the streak, rub the mineral on an unglazed porcelain plate and note the observed colour.

Reaction to Acid

These bubbles are caused by the release of a gas produced by the chemical reaction of the mineral and the acid. This phenomenon is seen in minerals composed of carbonates.

To check whether the mineral is effervescent, just place one drop or two of hydrochloric acid on the mineral and observe if bubbles appear.

Hardness

Some minerals can be softer, while others are much harder. To check hardness, scratch a mineral with a fingernail, nail, and steel file (or knife) and determine which objects can scratch the mineral.

To classify their minerals according to their hardness, we use the Mohs scale.

Cleavage and Fracture

To study cleavage, it is necessary to subject a mineral to an impact and analyze the breakage in the crystal structure.

Density

To determine the density, it is necessary to take the mass of the mineral and then determine its volume by water displacement.

Magnetism

To test the magnetism of a mineral, it is necessary to approach a magnet to a mineral and check whether there is attraction or repulsion between the mineral and the magnet.

Metallic minerals are made up of metallic elements. These can be melted down to obtain new products. Metallic minerals of metal origin represent more than half of all mineral resources in Quebec.

Metallic minerals have certain characteristics:

• they are generally related to igneous rocks;

• they are usually hard and shiny or have their own luster;

• they are ductile and malleable.

Industrial minerals represent nearly |30|% of all mineral rocks in Quebec. These minerals are non-metallic and are extracted from rocks to be used for industrial purposes.

Only four types of gemstones can be found in the world. However, when visiting a jewelry store or a boutique selling collectible minerals, there seems to be an endless number of them.

However, to earn the title of gemstone, a mineral must have the following characteristics:

• according to the Mohs scale, the hardness of a gemstone should range between 7.5 and 10;

• only one crystal is found in the gemstone;

• the gemstone must be aesthetically beautiful with respect to its colour and must be rare.

Gemstones are weighed in carats. One carat is equivalent to |200| mg of the mineral.

Here is a table that summarizes the main properties of the four gemstones available in the world.

Name of gemstone	Colour	Hardness (according to the Mohs scale)	Chemical composition	Usages
Diamond Source	Transparent	10	Carbon |(C)|	Jewelry, ophthalmic scalpels, electrodes
Sapphire Source	Blue	9	Aluminum oxide |(Al_{2}O_{3})|	Jewelry
Ruby Source	Red	9	Aluminum oxide |(Al_{2}O_{3})|	Jewelry, watchmaking, lasers
Emerald Source	Green	7.5	Aluminum and beryllium silicate |(Be_{3}Al_{2}(Si_{6}O_{18}))|	Jewelry

As can be seen, gold, garnet, topaz, quartz, amethyst, and turquoise are not gemstones. In fact, gold is a metal. Metals, like gold and silver, are not gemstones. As for other stones, they belong to the semi-precious stones category.

To be considered a semi-precious stone, the mineral must be quite hard and coarse; it must be transparent and of a beautiful hue. Finally, it must be relatively rare... or trendy.

With the development of science, humans have observed that certain elements of nature help plants to grow. However, on a large scale, these minerals can be devastating when spread as fertilizer in large quantities on farmlands. Plants are unable to absorb all these fertilizers. The excess is washed away by rainwater which carries it to rivers and lakes. This creates bioaccumulation and, in the short term, eutrophication of waterways.

Once the exploitation of a mine is finished, some companies leave the mine open. Scientists have noticed that these mines are a potential source of contamination. Indeed, the water that falls in these wells reacts with the minerals because it is an excellent solvent. By infiltration, this water travels in underground rivers until it reaches a water table. This accumulation of minerals leads, in the long term, to contamination of the water table. As a result, the surrounding populations can no longer use this water table, because it is unfit for consumption.

It should also be considered that for the construction of mines and mining, large amounts of water are used. This water, in contact with minerals, may be unfit for consumption.

Other major environmental impacts from mining or mineral processing are also likely to occur.

• There may be, in the medium or long term, a depletion of resources, since these minerals are not renewable resources.

• Large wooded areas can be destroyed when mines are developed, since roads must be built to access the mines, and factories are built nearby. In addition, the passage of heavy machinery over the ground compacts the soil.

• Greenhouse gases (GHGs) are emitted by the use of machinery in mines. In addition, heavy machinery also generates noise pollution.

• Wildlife will be displaced to other territories, driven away by humans exploiting mineral resources.