An obsolete term for low-Si chlorite.
An obsolete term for low-Si chlorite.
An obsolete manganese oxide name, now known as cryptomelane, see hollandite. Also, a term used to describe any massive, gray to black, hard, fine-grained manganese oxide material. Often, the latter material is romanechite.
Cf., wad, romanechite
A poorly defined material, possibly a decomposition product of hornblende consisting of mica and alkali pyroxene.
A poorly defined material, found as infillings in cavities in basic igneous rocks, possibly an altered chlorite or an iron-rich clinochlore.
An obsolete term for fine-grained muscovite or illite.
An obsolete term for fine-grained muscovite or illite.
See hydrotalcite group.
Pyrochroite, Mn(OH)2, structurally forms sheets of Mn(OH)6 octahedra and is isostructural with brucite. The structure is hexagonal closest packed. Pyrochroite occurs in low-temperature hydrothermal environments.
Cf., brucite
A property of crystals where an electric dipole moment develops in response to a temperature change. The material cannot exhibit temperature gradients, and the property diminishes over time at temperature. Only polar crystal classes exhibit this property. An analogous magnetic property, “pyromagnetism”, can also exist.