Specializing in the scientific study of the

Hardness is determined by comparison with other minerals. In the Mohs scale, a standard set of minerals are numbered in order of increasing hardness from 1 (talc) to 10 (diamond). A harder mineral will scratch a softer, so an unknown mineral can be placed in this scale, by which minerals; it scratches and which scratch it. A few minerals such as calcite and kyanite have a hardness that depends significantly on direction.  Hardness can also be measured on an absolute scale using a sclerometer; compared to the absolute scale, the Mohs scale is nonlinear.^[8]: 52
Tenacity refers to the way a mineral behaves, when it is broken, crushed, bent or torn. A mineral can be brittle, malleable, sectile, ductile, flexible or elastic. An important influence on tenacity is the type of chemical bond (e.g., ionic or metallic).^{[9]: 255–256}
Of the other measures of mechanical cohesion, cleavage is the tendency to break along certain crystallographic planes. It is described by the quality (e.g., perfect or fair) and the orientation of the plane in crystallographic nomenclature.
Parting is the tendency to break along planes of weakness due to pressure, twinning or exsolution. Where these two kinds of break do not occur, fracture is a less orderly form that may be conchoidal (having smooth curves resembling the interior of a shell), fibrous, splintery, hackly (jagged with sharp edges), or uneven.
If the mineral is well crystallized, it will also have a distinctive crystal habit (for example, hexagonal, columnar, botryoidal) that reflects the crystal structure or internal arrangement of atoms.^{[8]: 40–41} It is also affected by crystal defects and twinning. Many crystals are polymorphic, having more than one possible crystal structure depending on factors such as pressure and temperature.^{[5]: 66–68 [8]: 126}
Crystal structure[edit]

The perovskite crystal structure. The most abundant mineral in the Earth, bridgmanite, has this structure.^[10] Its chemical formula is (Mg,Fe)SiO₃; the red spheres are oxygen, the blue spheres silicon and the green spheres magnesium or iron.
Main article: Crystal structure
See also: Crystallography
The crystal structure is the arrangement of atoms in a crystal. It is represented by a lattice of points which repeats a basic pattern, called a unit cell, in three dimensions. The lattice can be characterized by its symmetries and by the dimensions of the unit cell. These dimensions are represented by three Miller indices.^{[11]: 91–92} The lattice remains unchanged by certain symmetry operations about any given point in the lattice: reflection, rotation, inversion, and rotary inversion, a combination of rotation and reflection. Together, they make up a mathematical object called a crystallographic point group or crystal class. There are 32 possible crystal classes. In addition, there are operations that displace all the points: translation, screw axis, and glide plane. In combination with the point symmetries, they form 230 possible space groups.^{[11]: 125–126}
Most geology departments have X-ray powder diffraction equipment to analyze the crystal structures of minerals.^{[8]: 54–55} X-rays have wavelengths that are the same order of magnitude as the distances between atoms. Diffraction, the constructive and destructive interference between waves scattered at different atoms, leads to distinctive patterns of high and low intensity that depend on the geometry of the crystal. In a sample that is ground to a powder, the X-rays sample a random distribution of all crystal orientations.^[12] Powder diffraction can distinguish between minerals that may appear the same in a hand sample, for example quartz and its polymorphs tridymite and cristobalite.^[8]: 54
Isomorphous minerals of different compositions have similar powder diffraction patterns, the main difference being in spacing and intensity of lines. For example, the NaCl (halite) crystal structure is space group Fm3m; this structure is shared by sylvite (KCl), periclase (MgO), bunsenite (NiO), galena (PbS), alabandite (MnS), chlorargyrite (AgCl), and osbornite (TiN).^{[9]: 150–151}
Chemical elements[edit]
See also: analytical chemistry

Portable Micro-X-ray fluorescence machine
A few minerals are chemical elements, including sulfur, copper, silver, and gold, but the vast majority are compounds. The classical method for identifying composition is wet chemical analysis, which involves dissolving a mineral in an acid such as hydrochloric acid (HCl). The elements in solution are then identified using colorimetry, volumetric analysis or gravimetric analysis.^{[9]: 224–225}
Since 1960, most chemistry analysis is done using instruments. One of these, atomic absorption spectroscopy, is similar to wet chemistry in that the sample must still be dissolved, but it is much faster and cheaper. The solution is vaporized and its absorption spectrum is measured in the visible and ultraviolet range.^{[9]: 225–226} Other techniques are X-ray fluorescence, electron microprobe analysis atom probe tomography and optical emission spectrography.^{[9]: 227–232}
Optical[edit]

Photomicrograph of olivine adcumulate from the Archaean komatiite of Agnew, Western Australia.
Main article: Optical mineralogy
In addition to macroscopic properties such as colour or lustre, minerals have properties that require a polarizing microscope to observe.