Do You Know What’s In Your Climbing Chalk?

Open Pit Mining


While at the core climber’s chalk is supposed to be just pure Magnesium Carbonate there are some observable differences between sources.

For all practical purposes we can simply state that “All chalk is the same” and “Chalk doesn’t matter” because the differences in chalk source have no practical observable effect on performance for climbers. The differences in chalk brands come down to how it feels, how fine the grind is and how it is packaged. All magnesium carbonate sources will perform similarly as long as basic care is taken during the manufacturing process.

As a manufacturer of liquid chalk we of course DO want to know exactly what is in the magnesium carbonate we source. Not because we think it will impact performance, but because we need to guarantee our chalk is free from contaminants and is produced in a way that is good for the environment. That’s why we run analyses and stick to certification guidelines for all materials we use.

While we can’t share the raw lab data we can share some interesting insights we gained from the X-ray Diffraction Spectrography and Thermogravimetric analysis one of our suppliers ran on multiple source of chalk.

X-ray diffraction allows you to detect common impurities like lead and arsenic because these impurities will show up as characteristic “peak signatures” on the graph. The thermogravimetric analysis heats the Magnesium Carbonate source and weighs the mass at increasing temperatures. This allows you to again define how pure the chalk is and how much moisture is captured inside the magnesium carbonate.

There were three sources in our analysis: chalk sourced from mines in China, chalk sourced from mines in Europe and chalk synthesised from seawater.

The X-ray Diffraction Spectrography data clearly showed that the magnesium carbonate sourced from mines in China contains contaminants not present in the samples mined in Europe or synthesised from seawater.

This was confirmed in the thermogravimetric measurement of the chalks where we clearly could again see the less pure Chinese chalk. In terms of moisture content the big take-away here is that magnesium carbonate synthesised from seawater has a clear advantage: there is a lot less “captured” H2O in the chemical structure and as such “seawater” chalk will have better absorption properties.

The most promising source of magnesium carbonate in the analysis has levels of impurities that are either undetectable or at a minimum 6x below EU standards for the following elements: Lead , Arsenic, Mercury, Chromium, Nickel, Zinc , Copper, Barium, Cadmium, Cobalt, Antimony, Selenium.

Based on this analysis we decided to switch a pure synthesised form of Magnesium Carbonate for all of our chalk products in summer 2021.

Photo by Francesco Ungaro