How to determine the density of a stone?

All minerals (and stones refer specifically to minerals) have two important characteristics - mass and density. And the density of the stone is important in a purely practical sense - to calculate the reserve of the mineral deposit.

What is this characteristic?

For any substance, the density is the mass divided by the unit volume. Since the stones (that is, the minerals) have an inhomogeneous composition and include elements of a different atomic mass, the physical characteristics of their density can vary considerably. Also, the density of the stones depends not only on the severity of the elements that make up them, but also on how tightly packed in their internal structure the elementary particles are.

Mineralogy deals with mineral density studies. The density of the stone is calculated by dividing the mass of the sample mineral in a unit volume by the mass of water of the same volume at a temperature of 4 ° C. For example, the weight of the sample is 200 grams. Water in the same volume 40 grams. In this case, the density of this stone will be equal to 5.

The density of stones is measured in kilograms per cubic meter or grams per centimeter cubic.

How to find the density of a stone?

How is the density of the stone determined? The procedure is quite simple - we weigh the sample first in the air, then in the water. According to Archimedes' law, the difference obtained corresponds to the mass of water that the sample displaces. The density is calculated by dividing the mass of the sample in air by the given difference.

Depending on the density, minerals can be light, medium, heavy and very heavy. For example, the density of granite stone is 2 600 kg / m³. For reference: lung density does not exceed 2.5 g / cm³, medium - varies from 2.5 to 4 g / cm³, heavy - from 4 to 8 g / cm³. Minerals with a density of more than 8 g / cm³ refer to very heavy stones.

Density of precious stones

In addition to the density and other characteristics - hardness, gemstone minerals or precious stones also have such an important component as the mass, measured in grams or carats (in pearls - in the grains).

To understand the ratio of these units, remember: 1 carat corresponds to 200 milligrams, in one grain is 50 milligrams, that is, 1 carat is equal to four grains. Accuracy of measuring gems - up to two decimal places.

Let's go to the laboratory

How to measure the density of dredges. Stones in the laboratory? The hydrostatic method is best for this. His principle was proposed by the Greek scientist Archimedes many centuries ago. The essence of the principle known from the school course of physics is this: a body immersed in a liquid is pushed out of it by force, which is equal to the weight of the fluid displaced by the given body.

In simple terms, if you hang a stone and put it in water, its weight will decrease in comparison with the original one by as much as the volume of water displaced by it. It is clear that this volume will be equal to the own volume of the stone.

Thus, by successively weighing the stones in the air, and then in the water, we can get all the data we need to calculate.

All - on nature!

Let us now turn to natural stone materials. They are known to exist in several ways. From a practical point of view, any breed is usually referred to one of two groups - strong or weak.

The materials of the first group have a high hardness index and, most often, a medium to coarse-grained structure. In the so-called non-winded state, they have a small water absorption. In other (low-strength) rocks, as the name implies, the strength is much lower. They also have a much higher degree of water absorption.

Sometimes when recognizing rocks of rock it is required to determine its hardness. In the field, it is most convenient to do this with the help of so-called. Relative scale of Mohs and additional improvised means. As such improvised means can be a pencil, a coin, a piece of glass, a file, a steel needle or a knife, an ordinary or a diamond glass cutter. The average density of the stone is also important in determining its breed. Having determined this value, you can identify the breed by referring to special tables.

Calculate the density of natural stones

How to calculate the average density of a sample stone? The equipment needed for this is a balance with a set of weights and the ability to measure the volume of a sample having an irregular shape.

The easiest way to do this is by having a graduated graduated cylinder with a capacity of about half a liter. In such a cylinder pour 200-300 ml of water and place a piece of the investigated stone material.

The total volume of samples placed in water is recognized by the amount of water displaced by them. Then, by dividing their mass by the calculated volume, the average density of the material is obtained .

What is important to consider?

It should be noted that this method is suitable only for dense rock with little water absorption (no more than 2%). If this characteristic is higher (up to 5%), the dry sample, previously weighed, must first be placed in an aqueous medium for saturation. Then the average density is determined by the above method. Saturation is considered complete, if the water absorption ceases to grow with water absorption.

Porous stones (most often limestones or tuffs) have low strength. They are easy to process - using an ordinary hacksaw for metal to cut out a sample of the desired shape (for example, a cube) and by counting the faces, calculate its volume.

Do it yourself

If there is no sufficient volume in the field conditions of a measuring cylinder, the amount of displaced water can be determined in the following way. In any metal vessel of a cylindrical shape, just below the top, an opening in the wall is punched by an ordinary nail, then a tube is inserted there, which can also be made independently by folding any film. Clamp it in the wall of the cylinder with plasticine or any similar material.

Thus, a walking volume measure is obtained. If this unit is used constantly, the tube makes sense to solder steel or brass.

Stones made by human hands

Everything written above was related to natural stones. And now it's time to talk about artificial ones too. They can be wall, road and airborne. This should include concrete roofing tiles and paving slabs, as well as all kinds of blind areas, stair steps and chimney elements.

In the production of virtually all of these stones, both in Russia and abroad strict technical standards are used. They regulate all the main characteristics - the quality of the raw materials, the size and shape of the section, the physical and mechanical properties (including the density of concrete stones).

These requirements depend on the expected operating conditions and available material.

What can be artificial stones?

Concrete, from which stones are made, can be heavy or light. Performed from it artificial stones, are made full-bodied or hollow. The normative characteristic of the average bulk density for hollow stones should not exceed 1 650 kg / m³, for full bodies - 2,200 kg / m³.

Wall stones in terms of average density (and, in addition, thermal conductivity) are considered effective (density up to 1,400 kg / m³), conditionally effective (1,400-1,650 kg / m³) and heavy (above 1,650 kg / m³). Most of them are now produced from lightweight concrete of low density (up to 1,800 kg / m³).

Heavy concrete (including sand) with high abrasion and low water absorption is used in the manufacture of bead or road stones, as well as paving slabs, as the conditions of their operation are more severe than those of wall.

There are artificial stones and filler, which can act quartz sand (it is considered a fine aggregate) or strong rocks (large aggregate). For example, the density of rubble from natural stone can be different depending on the fraction - the degree of grinding. The composition of the aggregate also has a considerable influence on the density of the artificial stone.