Loess

What it is

Loess is a loose, silt-sized mineral sediment deposited by wind, rich in quartz with some clay minerals and iron oxides that give it a yellow-brown colour. It has a long history in Korean and Chinese folk skincare as hwangto or yellow earth, and appears in Korean wash-off masks. In a formula it behaves as a mild absorbent and bulking powder rather than a strongly swelling clay.

What it does well

• Mild oil absorption with less tightening than bentonite

  Its silt-heavy, low-swelling structure means it mattifies without the pull of a smectite clay. The long record of traditional use is not matched by controlled clinical evidence.

  Traditional use

Worth knowing

• Composition varies with the deposit

  Loess is defined by how it was deposited rather than by a fixed mineralogy, so quartz content and trace metals differ between sources. Cosmetic-grade material is purified and tested, but this is an ingredient where the supplier matters.

  Matters most toBuyers of unrefined or DIY 'yellow earth' powders.

Where the EU stands