How Can The Mohs Scale Help the Lapidary Artist?

Can The Mohs Scale Help the Lapidary?

Richard Rockman Posted in Jewelry Making, Used Lapidary Equipment | No Comments »

The relative hardness of minerals is measured using the Mohs Scale. There are 10 minerals/levels of hardness on the Mohs Scale, the least hard is talc with a measurement of 1. The hardest mineral on the Mohs scale is the diamond with a measure of 10.There are also half measurements on the Mohs scale, 6.5, 7.5 for instance, but this article will not explore half measurements in any detail.

One of the ways a minerals "hardness" is determined is by the use of scratch test. If a mineral is can be scratched by a harder mineral, but not a softer one, then the mineral will have a Mohs scoring equal to or greater than the softer mineral but less than the harder mineral. For instance, Topaz has a Mohs 8 while Quartz has a Mohs rating of 7. So, if an unknown mineral can be scratched by Topaz but not by Quartz then the specimen will have a Mohs rating of 7.

Even though the scale attempts to define the hardness of a mineral, it is a relative score. It simply tells you that in comparison to another mineral, the sample specimen you are using is either harder or softer. For a lapidary, this can be helpful information when grinding down the specimen and when it is being polished.

The minerals on the Mohs scale, ranked from 1 to 10 are:

Talc
Gypsum
Calcite
Fluorite
Apatite
Orthoclase
Quartz
Topaz
Corundum
Diamond

You have probably found yourself looking at a mineral specimen in which you were uncertain about its identity. When faced with such a situation it can be helpful to know the Mohs scale to either help you identify the specimen, or, in the least to help you eliminate what the specimen isn't.

So, the next time you are getting ready to use your slab saw, lapidary equipment or faceting machine, don't forget the Mohs scale and how helpful it can be to you in identifying just what you're working with.