GEOL 102 Lecture Notes - Lecture 14: Aluminium Phosphate, Cabochon, Spider Web

• School: Queen's University
• Department: Geological Sciences and Geological Engineering
• Course: GEOL 102
• Professor: Ronald C Peterson

Document Summary

Why we love it: ro(cid:271)i(cid:374)"s egg (cid:271)lue (cid:272)olo(cid:396, spider web of veining, one of the first gems to be mined. Legacy of turquoise spans across the globe from ancient. Porous, semitranslucent to opaque mineral of hydrated copper and aluminum phosphate: Cual6(po4)4(oh)8:4h2o copper gives the blue color (cu2+: an aggregate of microscopic crystals that form a solid mass: closer packed crystals are less porous/has a finer texture, soft: hardness of only 5-6. Can be green, but full spectrum of grass green to sky blue of turquoise exist: peridote is green, color is valued: (cid:396)o(cid:271)i(cid:374)"s egg (cid:271)lue. Not faceted: usually in cabochons = polished. Porous: because it"s porous, can treat it with oil of wax to fill the pores (changes the refractive index) and makes them less chalky: can evacuate all the air and impregnate with acrylic. No light transmission --> no faceting: the color comes from reflection.