Orthoclase
Orthoclase with Carlsbad twin
Orthoclase is one of the most common minerals and is found worldwide. The original Carlsbad twins were described from Karlovy Vary (Carlsbad), Bohemia, Czech Republic. The samples consist of doubly terminated Orthoclase crystals twinned as penetrating Carlsbad Twins. A twinned crystal in which the twinning axis is the c axis, the operation is a rotation of 180 degrees, and the contact surface is parallel to the side pinacoid. It is quite common in the alkali feldspars. An alternative spelling is Karlsbad twin.
Orthoclase Feldspar
Orthoclase with Baveno and Manebach twins law
The elongated Orthoclase crystals exhibiting two combined forms of twinning: Baveno and Manebach. The Baveno law twin is a type of simple contact twin on the (021) plane exhibited by orthoclase, microcline and other members of the feldspar group. Famous samples with Baveno twin come from Baveno, Italy. A central twin plane following the Manebach law runs is distinctly visible from the front, but the diagonal Baveno law twin plane is visible on the termination.
Orthoclase feldspar coated with Epidote crystals
This specimen consists of creamy-pinkish crystals of Orthoclase feldspar richly coated with narrow black, acicular, and gemmy Epidote crystals to over 1 cm long.
Crystal structure of Orthoclase
Silicates - Tectosilicates
Crystal system - Monoclinic
Crystal class (Hermann-Mauguin) 2/m - Prismatic
Space group - C2/m
Orthoclase / RU Geology / by Grace Psenicska
Prismatic Orthoclase crystal (macro)
This is a single crystal of prismatic Orthoclase (untwinned) without matrix.
Pink prismatic Orthoclase crystal (macro)
This is a single crystal of pink prismatic Orthoclase (untwinned) without matrix.
A well-formed cluster of Orthoclase crystals
Orthoclase is one of the most common minerals and is found worldwide. The original Carlsbad twins were described from Karlovy Vary (Carlsbad), Bohemia, Czech Republic. This specimen is an excellent, well-formed cluster of Carlsbad-twinned Orthoclase crystals. The crystals are sharp, pearlescent gray. The Carlsbad twin is a penetrating twin, in which the twinning axis is the c axis, the operation is a rotation of 180 degrees, and the contact surface is parallel to the side pinacoid. It is quite common in the alkali feldspars. An alternative spelling is Karlsbad twin.
