Sepiolite is a clay mineral, a complex magnesium silicate, a typical formula for which is Mg4Si6O15(OH)2·6H2O. It can be present in fibrous, fine-particulate, and solid forms.
It was first described in 1847 for an occurrence in Bettolino, Baldissero Canavese, Torino Province, Piedmont, Italy. The name comes from a perceived resemblance of the material to the porous bones of the cuttlefish from the Greek, "sepion".
Because of its low specific gravity and its high porosity it may float upon water, hence its German name meerschaum ("sea foam").
Sepiolite is used in oil drilling and for cat litter. It is also used in a solid form for carving, where it is known as meerschaum. Owing to its fibrous mineral nature, sepiolite veins may contain the hazardous material, asbestos; even where asbestos is not present, sepiolite is often mistaken for it. Careful analytical techniques may be required to distinguish the two.