optical twinning
1Microcline — Optical properties Microcline Microcline feldspar Crystal System: Triclinic Color in PPL …
2feldspar — /feld spahr , fel /, n. any of a group of minerals, principally aluminosilicates of potassium, sodium, and calcium, characterized by two cleavages at nearly right angles: one of the most important constituents of igneous rocks. Also, felspar.… …
3Magnesiohastingsite — from Bratislava, Slovakia. Specimen size 4.5 cm General Category Amphibole …
4Calcite — A one inch Calcite Rhomb that shows the Double image refraction property. General Category Carbonate mineral …
5Fluorite — General Category Halide mineral Chemical formula CaF2 …
6Chondrodite — Not to be confused with Chondrite. Chondrodite Chondrodite from Franklin, New Jersey, USA General Category …
7Stilbite — from Kiui Island, Alaska, USA General Category Zeolite Chemical formul …
8Nyerereite — General Category Carbonate mineral Chemical formula Na2Ca(CO3)2 Strunz classification 05.AC.10 …
9Chalcophyllite — from the Ting Tang Mine, Carharrack, Cornwall, England. Photo by Rob Lavinsky General Category Arsenate minerals …
10Crystal oscillator — A miniature 4 MHz quartz crystal enclosed in a hermetically sealed HC 49/US package, used as the resonator in a crystal oscillator. A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal …
