You can identify a mineral by its appearance and other properties. The color and luster describe the appearance of a mineral, and streak describes the color of the powdered mineral. Each mineral has a characteristic density. Mohs Hardness Scale is used to compare the hardness of minerals.

streak

Most minerals, however, are usually white or colorless in a pure state. Many impurities can color these minerals and make their color variable.

Most minerals can be characterized and classified by their unique physical properties: hardness, luster, color, streak, specific gravity, cleavage, fracture, and tenacity.

Generally, color alone is not the best tool in identification because color can be highly variable. Some minerals can occur in a variety of different colors due to impurities in the chemical makeup of the mineral.

Explanation: It is common for one mineral to be naturally found in more than one color. Using color alone to identify a mineral could lead to an inaccurate conclusion. The hardness of the mineral, luster, cleavage, fracture, how it reacts to an acid, and other traits can be used to identify what the mineral is.

Mineral Identification Tests

• Luster: The quantity and quality of light reflected from the surface.
• Color: Obvious, but not always diagnostic.
• Streak: The color of the powdered mineral.
• Hardness: Hardness is the resistance of a mineral to scratching.

A few minerals appear to change color when viewed in different light. Streak is the color of a minerals powder when it is crushed. Some minerals have a different color powder than their actual color. Every mineral has an inherent streak no matter what color it is.

The best places to look for minerals are where there has been recent activity to create fresh exposures of rocks. This can include construction sites, new roads (including newly graveled areas), quarries, and mines.

hardness scale

For measuring the hardness of a mineral, several common objects that can be used for scratching are helpful, such as a fingernail, a copper coin, a steel pocketknife, glass plate or window glass, the steel of a needle, and a streak plate (an unglazed black or white porcelain surface).

The most common carbonate mineral in soils is calcium carbonate in the form of calcite. Two other polymorphs of calcium carbonate, aragonite and vaterite, also exist; however, neither is common in soils.

There are approximately 80 known carbonate minerals, but most of them are rare.

All carbonates have some water solubility and dissolve readily in acidic water. They dissolve in acidic water and can recrystallize from the water. Metal ions are frequently trapped in the lattice spaces during crystallization. This leads to carbonates with a variety of colors and crystal forms.

Nonsilicate minerals are organized into six major groups based on their chemical compositions: carbonates, halides, native elements, oxides, sulfates, and sulfides.

The main difference between the light and dark silicates is their relative specific gravities (densities); light silicates are less dense (lower specific gravity) than the dark silicates.

Many non-silicate minerals are economically important and provide metallic resources such as copper, lead, and iron….3.5: Non-Silicate Minerals.

quartz

“The Big Ten” minerals are: olivine, augite, hornblende, biotite, calcium-rich plagioclase (anorthite), sodium-rich plagioclase (albite), potassium-rich feldspar (commonly orthoclase), muscovite, quartz, and calcite.