How Is Climbing Chalk Made?

Climbing chalk or more commonly called magnesium carbonate in industry is traditionally mined as magnesite & then purified into the powder we all know as climbers.

Magnesium carbonate can also be made in the lab from magnesium salt and sodium bicarbonate. It can also be extracted from sea water but for practical reasons, most commercially available climbing chalk is purified from magnesite.

70% of all magnesite worldwide is mined in China & that is where most of our climbing chalk comes from. Mining is not exactly a clean process & sadly the whole region where chalk comes from has become extremely polluted. Think about that next time you chalk up. Our climbing chalk is actually mostly a by-product of other industries since magnesium carbonate is used in many other ways: in fire retardants, flooring, food, cosmetics & drugs. It’s exactly because our use in climbing is such a minuscule proportion of all magnesium carbonate use that makes it hard to ascertain the origin of chalk. We’re essentially last in line in the production process & can’t make too many demands with regards to its origin. This is of course true for many of the things we use as climbers: our ropes are made from byproducts in the petrochemical industry & our carabiners are made from metals mined in often dubious circumstances.

Magnesium carbonate is a stable, inert & pretty harmless chemical and is available at scale in different purities for both industrial use & even human consumption as food supplements. Climbers use magnesium carbonate because of its low solubility in water. In other words, it will keep your fingers dry. Climbing use only makes up a tiny fraction of all the magnesium carbonate produced worldwide.

The process of purifying magnesium carbonate is a pretty simple one involving many rounds of washing & baking the magnesite. To a certain extent, this can even be done at home with hydrochloric acid, baking soda, an oven & a lot of patience.

Some chalk sold commercially still contains some water in crystalline form. This is especially true for pharmacy-bought chalk or chalk bought as food supplements. Baking chalk tends to get rid of the excess moisture in it and is an easy DIY way to purify your own chalk.

Photo by Ivan Bandura