Hydrated clays mixed with paraffin, heated to 40-45
Hydrated clays mixed with paraffin, heated to 40-45
A modulated 2:1 layer silicate with continuous Mn-rich octahedral sheets and 6-fold tetrahedral rings forming islands three rings wide. These islands have inter-island linkages, some of which have inverted tetrahedra, involving 12-fold tetrahedral rings and double four-member rings, which act to link adjacent tetrahedral sheets (Eggleton and Guggenheim, 1994). A structural formula for parsettensite is M7.5(Mn,Mg)49(Si64.5Al7.5)Σ=72O168(OH)50 . nH2O. Parsettensite occurs in (low grade to very low grade) metasedimentary manganese ore deposits in Val d’Err, Oberhalbstein, Graubünden, Switzerland and on surfaces of pegmatite minerals by either hydrothermal or pneumatalytic processes at the Foote mine, Kings Mountain, North Carolina, USA, and in a very low grade metagraywacke and argillite near Otago, New Zealand.
Cf., stilpnomelane
A mechanical property where a mineral breaks along a planar or near-planar structural weakness. Parting usually results from plane-like defects, often twinning, or is produced by anisotropic stress. In contrast, cleavage is a property of the periodic crystal structure.
Cf., cleavage
An obsolete term for the Fe-free variety of bixbyite, alpha-(Fe,Mn)2O3.
A poorly defined material, possibly interstratified biotite and vermiculite.
An obsolete term for trilithionite.
An obsolete term for margarite.
Having a luster similar to that of mother-of-pearl with an interplay of rainbow-like colors (iridescent).
a) Peat is partially decomposed plant (humus) matter that formed in a nominally oxygen-free, water-saturated environment, often found in northern regions where microbial activity is limited. Peat has more than 30% dry mass of dead organic matter ranging from colloidal masses to recognizable plant residues.
b) In soil science, peat soil has a high content of plant-derived organic matter (humus), usually measured by the weight loss (or loss on ignition) by dry combustion in atmosphere. In peat soils, plant residues are recognizable. If the residual weight of an oven-dried (at 105-110oC) soil after dry combustion at 440oC is less than 75% of the weight of the oven-dried soil, then the soil is considered to be peat.
See peat.