Simple At Home Tests for Mineral Identification

With the thousands of varieties of minerals and rocks in existence, they can often be mistaken for one another. But each one holds distinctive properties that make it identifiable. Fortunately, with a few simple tests, you can easily identify your rocks right at home. Let’s consider three specific methods for identification such as the Mohs scale of hardness, streak tests, and gravity tests.

The Mohs Scale of Hardness:

The Mohs scale of hardness, devised by Friedrich Mohs in 1812, is a fundamental tool for mineral identification. It ranks minerals from 1 to 10 based on their scratch resistance against each other. For instance, a mineral with a higher ranking can scratch a mineral with a lower ranking. This scale aids in determining the relative hardness of a mineral compared to known reference minerals.

To conduct a Mohs hardness test, you'll need a set of common objects with known hardness levels, such as your fingernails (2.5), a copper penny (3.5), a steel nail (5.5), and a piece of glass (5.5). By attempting to scratch the mineral with these objects and observing the results, you can estimate its hardness level and cross-reference it with the Mohs scale for identification.

The Streak Test:

The streak test is another valuable method for identifying minerals, focusing on the color of the powdered form of a mineral. Unlike the mineral's external color, which can vary due to impurities, the streak color remains consistent and can provide crucial clues for identification.

Conducting a streak test is straightforward: simply rub the mineral against an unglazed porcelain tile or a piece of white, unglazed porcelain. The resulting streak left behind by the mineral can then be compared to a streak color chart for common minerals. This test is particularly useful when dealing with minerals that have a non-uniform or variable external color.

Understanding Gravity Tests:

Gravity tests, also known as specific gravity tests, assess the density of a mineral relative to the density of water. Since different minerals have distinct densities, this test can aid in narrowing down potential identifications.

To conduct a gravity test at home, you'll need a scale to measure the weight of the mineral both in air and when submerged in water. By dividing the weight in air by the difference between the weight in air and the weight in water, you can calculate the specific gravity of the mineral. Comparing this value to known specific gravity values for various minerals can help in identification.

 

Need directions on how to conduct your own simple tests at home? Check out our more comprehensive discussion here!