Tartan twinning

FIELD AND MICROSTRUCTURAL ANALYSIS OF A DIKE SWARM AND A ...

Exsolution, in the form of tartan twinning, is apparent in the orthoclase grains and embayments are observable within some quartz grains. Consertal textures (Janousek et al., 2004), represented by numerous subgrains, are observable in both quartz and feldspar grains

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December 12th,2019

Mineralogical Features Observed with Polarizing Light ...

Tartan Twinning Combination of albite twinning and pericline twinning in alkali feldspar results when high temperature sanidine (monoclinic) transforms to low temperature microcline (triclinic) is known as "tartan", "gridiron, or "cross-hatch" twinning pattern One of the most characteristic diagnostic properties

December 12th,2019

Tectosilicates – (Framework Silicates)

“tartan twinning”. The different types of twins observed in different minerals are known by their various twin lawstheir various twin laws. K-Fsp contain simple twins related by Carlsbad,,, p Baveno, albite or pericline laws, which are defined by orientation to crystallographic lattice. Twinning is not restricted to the feldspars.

December 12th,2019

FIELD AND MICROSTRUCTURAL ANALYSIS OF A DIKE SWARM AND A ...

Exsolution, in the form of tartan twinning, is apparent in the orthoclase grains and embayments are observable within some quartz grains. Consertal textures (Janousek et al., 2004), represented by numerous subgrains, are observable in both quartz and feldspar grains

December 12th,2019

Potassium Feldspars 3O8 - MIT OpenCourseWare

tartan twinning (see fig 15-18). Orthoclase is optically monoclinic K-spar with a 2V greater than 40°. Sanidine is also optically monoclinic but has a much lower 2V (0-40°). Adularia is a low-temperature hydrothermally produced mineral and will not be seen in this lab. Feldspar textures: A variety of intergrowth and exsolution

December 12th,2019

LAB 4: COMMON MINERALS IN SEDIMENTARY ROCKS

that is referred to as tartan twinning . Orthoclase displays either no twinning, or simple Carlsbad twinning in which the crystal is divided in half by a twin plane. Orthoclase occurs most commonly in volcanic rocks. Examine hand samples 596 (microcline), 313 (orthoclase), and 10 (microcline, var. amazonite).

December 12th,2019

LAB 3: COMMON MINERALS IN SEDIMENTARY ROCKS, Part 1

LAB 3: COMMON MINERALS IN SEDIMENTARY ROCKS, Part 1 ... reversal of optic sign, and the characteristics of twinning. ... hatched pattern that is referred to as tartan twinning (photo to right). Orthoclase displays either no twinning, or simple Carlsbad twinning in which the crystal is divided in half by a twin ...

December 12th,2019

OPTICAL PROPERTIES: Orthopyroxene, Feldspar and Olivine

OPTICAL PROPERTIES: Orthopyroxene, Feldspar and Olivine FELDSPAR TWINNING Cross-hatch or tartan twinning in microcline Polysynthetic, lamellar or albite twinning in plagioclase Zoning -- not true twinning but forms during crystallization which forms solid solutions. Imperfect reaction between the solid phase and liquid phase may result in chemical

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