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- https://geo.libretexts.org/Bookshelves/Geology/Gemology/07%3A_Optical_Properties_of_Gemstones
- https://geo.libretexts.org/Bookshelves/Geology/Gemology/16%3A_Gemstones/16.08%3A_Garnet/16.8.03%3A_GrossularWithin this group, Merelani Mint garnet is a grossular variety that is found in the Merelani Hills of Tanzania. Tsavorite (or tsavolite) is a grossular that, like the Meralani mint, is green in colour...Within this group, Merelani Mint garnet is a grossular variety that is found in the Merelani Hills of Tanzania. Tsavorite (or tsavolite) is a grossular that, like the Meralani mint, is green in colour. The distinction between a 'regular' green grossular and tsavorite is commonly thought to be a function of saturation and tone. Mali garnet is a yellow-green variety of grossular with a slight overlap in the grossular-andradite series.
- https://geo.libretexts.org/Bookshelves/Geology/Gemology/16%3A_Gemstones/16.32%3A_DiasporeFigure \PageIndex1: Color-changing diaspore from green in daylight to brown in incandescent light - also known as “Zultanite” in the gem market. When Zultanite Gems LLC acquired the mining locat...Figure \PageIndex1: Color-changing diaspore from green in daylight to brown in incandescent light - also known as “Zultanite” in the gem market. When Zultanite Gems LLC acquired the mining location, this color-change variety of diaspore was marketed under the tradename "zultanite®". At present (2007) sole distribution rights of "zultanite®" are granted to GemsTV. Diaspore may be confused with peridot due to the strong doubling of back facets, but diaspore is usually much paler in color.
- https://geo.libretexts.org/Bookshelves/Geology/Gemology/09%3A_Specific_Gravity
- https://geo.libretexts.org/Bookshelves/Geology/Gemology/16%3A_Gemstones/16.07%3A_ZoisiteZoisite Chemical composition Calcium aluminum silicate Crystal system Orthorhombic Habit Prismatic and massive Cleavage Perfect, prismatic Fracture Uneven Hardness Optic nature Biaxial + Refractive in...Zoisite Chemical composition Calcium aluminum silicate Crystal system Orthorhombic Habit Prismatic and massive Cleavage Perfect, prismatic Fracture Uneven Hardness Optic nature Biaxial + Refractive index 1.685-1.707 Birefringence 0.008 Dispersion Low, 0.012 Specific gravity 3.35 Lustre Vitreous Pleochroism Strong in blue Figure \PageIndex1: Zoisite with ruby bead
- https://geo.libretexts.org/Bookshelves/Geology/GemologyThe Gemology Project is a non-profit gemstone and gem science wiki-style database for anyone interested in gemstones and gemology.
- https://geo.libretexts.org/Bookshelves/Geology/Gemology/16%3A_Gemstones/16.47%3A_LarimarLarimar Chemical composition NaCa 2 Si 3 O 8 (OH) Crystal system Triclinic Habit Aggregate Hardness Optic nature Biaxial + Refractive index 1.59 - 1.63 Birefringence 0.028-0.038 Dispersion Very weak S...Larimar Chemical composition NaCa 2 Si 3 O 8 (OH) Crystal system Triclinic Habit Aggregate Hardness Optic nature Biaxial + Refractive index 1.59 - 1.63 Birefringence 0.028-0.038 Dispersion Very weak Specific gravity 2.62 - 2.87 Lustre Silky Fluorescence Yellow or orange (SW-UV) A blue pectolite found in the Dominican Republic. See pectolite Acknowledgments and External Links Gems & Gemology, Winter 1989 Issue Larimar Blue Pectolite from the Caribbean
- https://geo.libretexts.org/Bookshelves/Geology/Gemology/16%3A_Gemstones/16.06%3A_Quartz_-_Polycrystalline/16.6.01%3A_Chalcedony/16.6.1.04%3A_CarnelianCarnelian Chemical composition Silicon dioxide SiO 2 Crystal system Trigonal Habit Aggregate Hardness 6.5 - 7 Refractive index ± 1.54 Specific gravity 2.55 - 2.70 Lustre Vitreous Figure \(\PageIndex{1...Carnelian Chemical composition Silicon dioxide SiO 2 Crystal system Trigonal Habit Aggregate Hardness 6.5 - 7 Refractive index ± 1.54 Specific gravity 2.55 - 2.70 Lustre Vitreous Figure \PageIndex1: Carnelian cabochon
- https://geo.libretexts.org/Bookshelves/Geology/Gemology/16%3A_Gemstones/16.06%3A_Quartz_-_Polycrystalline/16.6.01%3A_Chalcedony/16.6.1.05%3A_ChrysopraseChrysoprase Chemical composition Silicon dioxide SiO 2 Crystal system Trigonal Habit Aggregate Hardness 6.5 - 7 Refractive index ± 1.54 Specific gravity 2.55 - 2.70 Lustre Vitreous Figure \(\PageIndex...Chrysoprase Chemical composition Silicon dioxide SiO 2 Crystal system Trigonal Habit Aggregate Hardness 6.5 - 7 Refractive index ± 1.54 Specific gravity 2.55 - 2.70 Lustre Vitreous Figure \PageIndex1: Chrysoprase Cabochon Photo courtesy of Rick Martin
- https://geo.libretexts.org/Bookshelves/Geology/Gemology/16%3A_Gemstones/16.43%3A_JeremejeviteWebster (1994)describes jeremejevite as an hexagonal crystal with a uniaxial negative optic character in his Identification Tables, however in the text of the same book, he refers to it as an orthorho...Webster (1994)describes jeremejevite as an hexagonal crystal with a uniaxial negative optic character in his Identification Tables, however in the text of the same book, he refers to it as an orthorhombic crystal with a biaxial optic character. The crystal character of the inside of the crystal is different from that of the outside of the crystal.
- https://geo.libretexts.org/Bookshelves/Geology/Gemology/10%3A_Basic_Math_for_Gemology
