A complex magnesium silicate, a typical chemical formula for which is Mg4Si6O15(OH)2·6H2O, it can be present in fibrous, fine-particulate, and solid forms.

The fibrous clay minerals have recently been shown to exist as a continuous polysomatic series where the endmembers are sepiolite and palygorskite.

[7] Sepiolite is opaque and off-white, grey or cream colour, breaking with a conchoidal or fine earthy fracture, and occasionally fibrous in texture.

Sepiolite can be identified in hand specimen by applying a drop of a saturated solution of methyl orange on the sample.

[14] The best-known deposits of the material used in the manufacture of pipes and decorative objects (meerschaum) is obtained chiefly from the plain of Eskişehir in Turkey, between Istanbul and Ankara.

[7] In the United States, it occurs in serpentine in Pennsylvania (as at Nottingham, Chester County) and in South Carolina and Utah.

[9][10][18] The positive environment effect in the arid region is that sepiolite increases plant available water in the sandy soils.

[19] A negative effect is that the cemented sepiolite causes considerable geotechnical and geometallurgical difficulty for extracting the heavy minerals from the sepiolite-rich sands.

[18] Meerschaum has occasionally been used as a substitute for soapstone, fuller's earth, and as a building material; but its chief use is for smoking pipes and cigarette holders.

[7] The first recorded use of meerschaum for making pipes was around 1723 and quickly became prized as the perfect material for providing a cool, dry, flavourful smoke.

[7] The crudely shaped masses thus prepared are turned and carved, smoothed with glass-paper, heated in wax or stearine, and finally polished with bone ash, etc.

[21] Imitations are made in plaster of Paris treated with paraffin and dyed with two types of coloured tree resins; Gamborge and Dragon's blood.

The soft, white, earthy mineral from Långbanshyttan, in Värmland, Sweden, known as aphrodite (Greek: sea foam), is closely related to sepiolite.

[24] Processes for bacterial transformation based on the Yoshida effect can utilize sepiolite as an acicular nanofiber.