Garnet

A hard, dense and reusable silicate mineral, used for abrasive blasting, waterjet cutting and water filtration.

Industrial minerals · No. 69

• Not on a critical list

Garnet, the gemstone of Anglo-Saxon jewellery, now blasts ship hulls and cuts steel in waterjets, and can be reused several times.

Chart: Illustration: Garnet

Where it comes from

Chart: Map of where it comes from

Industrial garnet, mostly almandine, comes from gneisses, schists and heavy-mineral sands. Australia and India dredge beach and river sands, while New York mines gneiss near North Creek.

Three things to know

1. South Africa's garnet mine suspended work in November 2024, cutting its output from 40,000 t to zero.
2. Garnet contains almost no free silica, making it a safer substitute for silica sand in blasting and the standard waterjet abrasive.
3. Plants in Oregon and Pennsylvania, with capacities of 16,000 and 25,000 tons a year, recycle used garnet.

The journey

1. 1 OreGneiss, schist or heavy-mineral sand
2. 2 MiningOpen pit or dredge
3. 3 SeparationGravity and magnetic separation
4. 4 GradingCrushed, screened into mesh sizes
5. 5 End usesBlasting abrasive, waterjet cutting, filter media

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