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Today this tourmaline locality (type locality for dravite) at Dobrova (near Dravograd), is a part of the Republic of Slovenia. [9] Tschermak gave this tourmaline the name dravite, for the Drava river area, which is the district along the Drava River (in German: Drau, in Latin: Drave) in Austria and Slovenia.
The "chelsea" filter was originally devised by Anderson and Payne in 1934 of the Gem testing Laboratory of the London Chamber of Commerce & Industry.The filter was devised with the collaboration of gemmology students of the Chelsea College of Science and Technology where Basil Anderson was an instructor for the Gemmological Association of Great Britain.
In 1747 Linnaeus first related the phenomenon to electricity (he called tourmaline Lapidem Electricum, "the electric stone"), [10] although this was not proven until 1756 by Franz Ulrich Theodor Aepinus. [11] Research into pyroelectricity became more sophisticated in the 19th century. In 1824 Sir David Brewster gave the effect the name it has ...
Tourmaline “A favorite stone of gem collectors for its beautiful crystalline structure and tonal variety from pink to blue-green, tourmalines are a heart-centric stone that can enhance self-love ...
Some materials used (especially gallium phosphate or tourmaline) are extremely stable at high temperatures, enabling sensors to have a working range of up to 1000 °C. Tourmaline shows pyroelectricity in addition to the piezoelectric effect; this is the ability to generate an electrical signal when the temperature of the crystal changes. This ...
Gemstone irradiation is a process in which a gemstone is exposed to artificial radiation in order to enhance its optical properties.High levels of ionizing radiation can change the atomic structure of the gemstone's crystal lattice, which in turn alters the optical properties within it. [1]
Elbaite, a sodium, lithium, aluminium boro-silicate, with the chemical composition Na(Li 1.5 Al 1.5)Al 6 Si 6 O 18 (BO 3) 3 (OH) 4, [4] is a mineral species belonging to the six-member ring cyclosilicate tourmaline group. Elbaite forms three series, with dravite, with fluor-liddicoatite, and with schorl.
According to the New York Times, here's exactly how to play Strands: Find theme words to fill the board. Theme words stay highlighted in blue when found.