How is density used to identify a mineral

The mineral is put into the beaker with water, and the water level rises. The difference in the amount of water before the specimen was put in and after it was put in is noted. The mineral is taken out, and the water is spilled out.

Then the beaker is filled with the amount of water that the specimen displaced and measured. The difference in weight of the beaker when it was empty and the current measurement the beaker with the displaced water is the weight of the displaced water. The weight of the displaced water has the same volume as the specimen, but a different mass. The weight of the specimen is divided by the weight of the displaced water, and that number attained is the specific gravity of that specimen.

This test cannot be conducted for an embedded mineral, but only for a single crystal or mass, for obvious reasons. He was so excited he forgot that he had no clothes on. A mineral is something that is produced by the earth and not by plants, animals, or people. Coal is not a mineral; it is made from decomposed plants that have been fossilized. You can find the density of an object by taking its mass, which is how heavy it is, and dividing it by the volume, its size.

Then you drop some ice cubes in the cup. Then the water rises up because the ice cubes displaced water. The amount of water that is displaced is equal to the volume of the object. By capturing this water and measuring it, using a graduated cylinder, you can find an exact measurement. Globular - radiating individual crystals that form spherical groups.

Drusy - small crystals that cover a surface. Stellated - radiating individuals that form a star-like shape. Some minerals characteristically show one or more of these habits, so habit can sometimes be a powerful diagnostic tool.

Cleavage, Parting, and Fracture. Crystals often contain planes of atoms along which the bonding between the atoms is weaker than along other planes. In such a case, if the mineral is struck with a hard object, it will tend to break along these planes. This property of breaking along specific planes is termed cleavage. Because cleavage occurs along planes in the crystal lattice, it can be described in the same manner that crystal forms are described. Thus, if the mineral belongs to the tetragonal crystal system it should also cleave along faces parallel to , because and are symmetrically related by the 4-fold rotation axis.

The mineral will be said to have two directions of cleavage. But if we are referring to cleavage directions, the mineral only has two, because the cleavage planes 0 0 and 00 are parallel to, and thus in the same direction as and The cleavage can also be described in terms of its quality, i.

Note: Please do not attempt to cleave the minerals in the laboratory. Many of the specimens you examine cannot be readily replaced. Cleavage is usually induced in the mineral when it is extracted from the rock when it is found, and can usually be seen as planes running through the mineral. Therefore, you do not have to break the mineral in order to see its cleavage. Cleavage can also be described by general forms names, for example if the mineral breaks into rectangular shaped pieces it is said to have cubic cleavage 3 cleavage directions , if it breaks into prismatic shapes, it is said to have prismatic cleavage 2 cleavage dir ections , or if it breaks along basal pinacoids 1 cleavage direction it is said to have pinacoidal cleavage.

For examples, see figure 2. Parting is also a plane of weakness in the crystal structure, but it is along planes that are weakened by some applied force. It therefore may not be apparent in all specimens of the same mineral, but may appear if the mineral has been subjected to the right stress conditions.

If the mineral contains no planes of weakness, it will break along random directions called fracture. Several different kinds of fracture patterns are observed. Hardness is determined by scratching the mineral with a mineral or substance of known hardness. Hardness is a relative scale, thus to determine a mineral's hardness, you must determine that a substance with a hardness greater than the mineral does indeed scratch the unknown mineral, and that the unknown mineral scratches a known mineral of lesser hardness.

Hardness is determined on the basis of Moh's relative scale of hardness exhibited by some common minerals. These minerals are listed below, along with the hardness of some common objects. Several precautions are necessary for performing the hardness test. If you attempt to scratch a soft mineral on the surface of a harder mineral some of the softer substance may leave a mark of fine powder on the harder mineral. This should not be mistaken for a scratch on the harder mineral.

A powder will easily rub off, but a scratch will occur as a permanent indentation on the scratched mineral. Some minerals have surfaces that are altered to a different substance that may be softer than the original mineral. A scratch in this softer alteration product will not reflect the true hardness of the mineral. Always use a fresh surface to perform the hardness test. Sometimes the habit of the mineral will make a difference. For example aggregates of minerals may break apart leaving the impression that the mineral is soft.

Or, minerals that show fibrous or splintery habit may break easily into fibers or splinters. It is therefore wise to always perform the hardness test in reverse.

If one mineral appears to scratch another mineral, make sure that the other mineral does not scratch the apparently harder mineral before you declare which of the minerals is harder. Minerals such as quartz have a non-metallic luster. Different types of non-metallic luster are described in Table below. Can you match the minerals in Figure below with the correct luster from Table above?

Mass is a measure of the amount of matter in an object. The amount of space an object takes up is described by its volume. The density of an object depends on its mass and its volume. For example, the water in a drinking glass has the same density as the water in the same volume of a swimming pool.

Quartz is even less dense than pyrite and has a density of 2. The specific gravity of a substance compares its density to that of water. Substances that are more dense have higher specific gravity. Hardness is a measure of whether a mineral will scratch or be scratched. Mohs Hardness Scale, shown in Table below , is a reference for mineral hardness.

With a Mohs scale, anyone can test an unknown mineral for its hardness. Imagine you have an unknown mineral. You find that it can scratch fluorite or even apatite, but feldspar scratches it. Note that no other mineral can scratch diamond. Breaking a mineral breaks its chemical bonds.

Since some bonds are weaker than other bonds, each type of mineral is likely to break where the bonds between the atoms are weaker. For that reason, minerals break apart in characteristic ways. Cleavage is the tendency of a mineral to break along certain planes to make smooth surfaces.