Learning Geology Alexandrite Gemstone

Learning Geology Alexandrite Gemstone Its physical and optical properties include: hardness: alexandrite is a relatively hard gemstone, with a mohs hardness of 8.5 on a scale of 1 to 10. this makes it durable and suitable for use in jewelry. refractive index: the refractive index of alexandrite ranges from 1.746 to 1.755, which is relatively high. Forming of alexandrite. alexandrite is the rare colour change variety of the mineral chrysoberyl. its rarity is a result of its unlikely chemical makeup. alexandrite can only form when aluminium and beryllium combine with trace elements like iron, titanium and, most importantly, chromium. on rare occasion, vanadium may also be present.

Learning Geology Alexandrite Gemstone Geographic origin determination of alexandrite. figure 1. a group of rings featuring alexandrite from brazil. top row, left to right: a three stone alexandrite ring with a 1.35 ct center oval flanked by two smaller ovals with a combined weight of 1.29 carats and a ring with a 1.32 ct kite shaped center stone flanked by two kite shaped diamonds. 16.12.01: alexandrite. alexandrite is a phenomenal variety of the mineral chrysoberyl. because of the trace amounts of the chromophores vanadium and chromium, alexandrite appears different colors depending on whether it is viewed in natural or incandescent light. in daylight, the stone appears to be green; in artificial light it appears to be. To identify alexandrite, observe its color change from green in daylight to red in incandescent light. it’s typically transparent with minor inclusions. perform a streak test (white streak), magnet test (slight response), and hardness test (scratch with steel file). alexandrite shows single refraction and has a specific gravity around 3.73. One of the finest brazilian alexandrites, the “whitney alexandrite” can be found at the smithsonian museum of natural history. weight: 17.08 carats. estimated value: unknown. its finest dual colors are a bluish green in daylight and fluorescent light, and an intense purple, pink, or red in incandescent light.