Guide to Identify Minerals
In this guide we will see how to identify minerals, which is somewhat complicated, since to obtain an accurate result, you should check its internal structural characteristics, perform a chemical analysis and see how its particles are arranged and what elements it is composed of.
First of all, we must know that each type of mineral has a series of properties, which makes it different from the rest and we can identify it, so you will have to know in advance the properties of the mineral that you think you have, to know how to identify it. minerals we are going to focus on the physical properties.
1 - Color, how to know type of mineral.
Initially we must look at the color of the mineral, although it is not a reliable test, we can get a basic idea of what we may have, although it is easy to get confused, since there are very similar minerals in terms of appearance, but it is a first step that It will help you rule out possibilities, it is the initial test that could not be missing to know how to identify minerals.
Here you can see two minerals that have a similar color and can create confusion, so it is not enough to determine the type of mineral.
2 - Luster, ways to identify minerals.
The luster of a mineral is the way it reflects light and can range from a bright metallic luster to a dull, matte appearance.
The metallic shine is characteristic of minerals that have an appearance similar to metals, presenting a brilliant and reflective shine. Some common examples are pyrite, gold, silver, and native copper.
Within the non-metallic shine, we can find various variations ranging from vitreous shine to matte. The vitreous shine resembles that of polished glass, it is characteristic of minerals such as quartz, on the other hand, the adamantine shine occurs in minerals that appear to be covered by a thin layer of oil, such as diamond, in addition, there are various shines , the resinous one like serpentine, the pearly one like talc, the silky one like chrysotile, which provide a wide range of textures and appearances, the matte shine is found in minerals such as kaolinite or iron oxides, and has a completely opaque and no shine.
How to identify minerals is not a simple task, but if you take into account their physical properties you will be able to identify them.
3 - Form and Habit, how to identify minerals.
We can find different crystalline formation structures, which present external geometric shapes, characteristic of some minerals, which makes identification easier, but others in other cases present formations added to other minerals or massive formations, and by not having a defined shape makes it more complicated. Depending on the type of shape that the crystals have, we talk about habits.
We can find many types of habit, those that we have already seen such as the prismatic habit (quartz, calcite…), the tabular habit (gypsum, barite), equidimensional (pyrite, fluorite, halite, galena), laminar (phlogopite, muscovite, biotite), fibrous (gypsum), massive, botroidal, among others.
4 - Hardness, check type of mineral.
Hardness is determined based on the resistance that a mineral presents when scratched with another material. We are based on the Mohs scale, a very simple classification that allows us to order minerals from the softest to the hardest. This scale has a total of 10 divisions, from 1, the softest mineral such as talc, to 10 which is the hardest, the diamond.
In order to carry out the test we must know the hardness of some elements that serve as a reference, such as a fingernail, with an approximate hardness of 2.5, or a copper coin, with an approximate hardness of 3.5, which You will be able to scratch calcite easily, but you will not be able to or will have a hard time scratching fluorite. An element of medium hardness that we can have at our disposal is glass, with an approximate hardness of 5.5. We can also take as reference a steel knife with an approximate hardness of 6.5.
Escala de Mohs
- 1-Talc, It can be easily scratched with a fingernail.
- 2-Plaster, It can be scratched with a fingernail with more difficulty.
- 3-Calcite, It can be scratched with a copper coin.
- 4-Fluorite, It can be scratched with a steel knife.
- 5-Apatite, It can be difficult to scratch with a knife.
- 6-Orthoclase, It can be scratched with steel sandpaper.
- 7-Quartz, Scratches the glass.
- 8-Topaz, Scratched by tungsten carbide tools.
- 9-Corundum, Scratched by silicon carbide tools.
- 10-Diamond, The hardest, cannot be scratched except with another diamond.
5 - Stripe, mineral identification.
We are going to see another of the tests that we can carry out to know how to identify minerals, we must check the scratch or imprint of the mineral, which is nothing more than the color that the mineral presents when it is in a powder state when scratched on a porcelain plate. unglazed white porcelain prepared for it, but any piece of unglazed white porcelain can serve, such as the back of some plates.
The stripe of a mineral is not necessarily the same color tone as the piece, so it can be a useful check in some cases.
6 - Exfoliation and Fracture, types of minerals.
The exfoliation of a mineral is conditioned by the internal structure of the mineral and is constant for each type. It is due to the existence of crystallographic planes where they tend to break more easily, unlike fracture, which refers to random breakage. , without being related to the internal structure of the mineral as happens with exfoliation.
Not all minerals have exfoliation, and sometimes it is so weak that it cannot be seen with the naked eye. In other cases we will have samples in which no crystals can be seen, but there is exfoliation.
The simplest way to check this property is by hitting the piece and observing the fracture surface, looking for shapes that correspond to these planes.
If after carrying out all these tests you have still not been able to reach any conclusion, you can carry out other types of tests such as fluorescence, clarity, density, reaction to acid, magnetism, etc.
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