Pyrophyllite or Agalmatolite, Aluminum Silicate Hydroxide (Al Si2 O5 OH), is a common clay mineral, although good specimens that show radiating crystal growth are very rare, with the best examples coming from the American states of California, Georgia and North & South Carolina. It is also mined at Beresovsk in the Ural Mountains and Ottosdal, South Africa, where it is marketed as 'wonderstone' and used for sculpture and carvings. The name of the mineral was given by R. Hermann in 1829 and derives from the Greek for 'fire leaf'. Pyrophyllite is one of the 'leaf silicates', so called because they form with a sheet-like structure, each layer of mineral unconnected to the layers above and below it, giving them a flaky fracture. If it is heated above about 800 degrees C the mineral's water content evaporates and it collapses into a pile of leaf-like flakes. In older literature Pyrophyllite is often called Agalmatolite, but today this term tends to apply to a variety of Pyrophyllite used by Chinese artisans for small sculptures and ornate carvings.

There are two distinct types of Pyrophyllite, one being monoclinic and the other triclinic, but their properties are identical and the two forms are often found together, sometimes intergrown with each other, so they are usually treated as one mineral. Pyrophyllite is an isomorph of talc - both minerals share the same structure but have different chemical compositions (talc contains magnesium where Pyrophyllite contains aluminum).

Color is usually white, gray or yellow with occasional pale green and blue specimens. Reddish-brown colors are caused by iron oxide staining. Luster is greasy to dull, but pearly on broken crystal surfaces. Cleavage is perfect in one direction, fracture splintery, streak is white, hardness usually 1 - 1.5 (soft enough to be scratched by a fingernail) and specific gravity 2.65 - 2.85.

Pyrophyllite is believed to enhance receptive psychic techniques, especially clairvoyance, clairaudience and automatic writing. It is said to be helpful during meditation, keeping the mind and flow of thoughts flexible even while concentrated on one single point. Working with Pyrophyllite is said to help align the chakras, enhancing physical and mental health by encouraging a free flow of energy through the body.

Pyrophyllite was once used in magic and charms to protect from fire, poisons and evil spirits. Because it is a clay mineral it can be used in beauty products to treat the skin, and is usually sold as 'healing clay' or 'pyro-clay'. Used as a face mask it can help cleanse, purify and encourage better circulation in the tiny capilaries of the face, softening the skin and improving the complexion. It is used by some healers for internal cleansing and energy balancing, usually ground to a powder and mixed into a healing herbal tonic.