How to Calculate Rock Abrasion

While defined as solid naturally occurring minerals, rocks can actually be as soft as talcum powder or as hard as diamonds. Rock has myriad uses in society. From bath powder to a diamond engagement ring, from marble-clad high rises to gravel driveways, rock — in its many forms — is an integral part of daily living. Scientists regularly subject rock to property tests, tracking characteristics such as color, luster, and hardness. A scratch — or abrasion — test was first developed by Fredriech Mohs in 1822. The Mohs scale ranks rocks from 1 (softest rock forms) to 10 (hardest rock forms). For industrial purposes today, rock abrasion resistance is most often calculated through use of the Los Angeles Abrasion Machine. However, the home-based rock hound can also test for rock abrasion with a simple set of tools.

Things You'll Need

• Rock samples
• Nail
• Set of Mohs scale rock samples
• Hand magnifying lens

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Instructions

1. • 1

     Find a good surface (fairly flat) on the rock sample.

   • 2

     Scratch the rock surface, pressing firmly with the nail on the rock sample. Try to scratch with the rock grain.

   • 3

     Rub aside any powder for observing the resulting scratch.

   • 4

     View the scratch through the hand magnifying lens.

   • 5

     Compare the scratch with those administered to the Mohs scale rock samples for likeness; eliminate any Mohs scale samples that are not similar in scratch appearance. The closest match between the sample rock and the Mohs scale standard rock is the hardness rating of the rock sample.