An obsolete local, varietal term for antigorite serpentine of various colors, but typically green, from West Chester, Chester County, Pennsylvania, USA.
An obsolete local, varietal term for antigorite serpentine of various colors, but typically green, from West Chester, Chester County, Pennsylvania, USA.
A member of the palygorskite-sepiolite group with a composition of approximately (Ca1.68Mn0.32)Fe3+2.96(Si7.87 Al0.08)O20(OH)4. 10H1.98O.
See palygorskite-sepiolite group
An obsolete varietal term for biotite.
See pyroxenoid group.
A trioctahedral mica that shows interlayer deficiency. It is a series name (Rieder et al., 1998) with a generalized composition of Na0.5v0.5Mg2.5Al0.5(AlSi3)O10(OH)2, where = vacancy The formula indicates that it is not an end-member composition. Series names designate that additional research may be warranted.
See hydrotalcite group.
An obsolete varietal term for biotite.
The Wulff rule or Gibbs-Curie-Wulff Theorem states that when the surface free energy of a crystal is minimized at equilibrium conditions, the perpendicular distance from a given crystal face to the center of the crystal divided by the surface free energy of that face is a constant for all faces of the crystal.
An obsolete term, see western bentonite.
An obsolete term, see western bentonite.