Description
The mineral kyanite, or disthene, is an aluminum silicate with the chemical formula Al2SiO5. It belongs to the nesosilicate group. This blue, gray, white, green, or black mineral has perfect cleavage along the crystal plane [100], a white streak color, and a vitreous to pearlescent luster. Its crystal system is triclinic, its average density is 3.61, and its hardness is 4 to 7. Kyanite is neither magnetic nor radioactive. The name of the mineral kyanite is derived from the Greek word kyanos, meaning "blue." Kyanite is a very common mineral found in many rocks. It occurs, among other places, in metamorphosed sedimentary rocks. Along with the other aluminum silicates sillimanite and andalusite, it is also an indicator of the depth and temperature at which a rock has undergone metamorphism. Kyanite is generally stable at temperatures below 650°C and at pressures exceeding 0.3 GPa (gigaPascals). Pressure and temperature are related, requiring a higher temperature (600°C) at high pressures (0.6 GPa) to form sillimanite from kyanite. At pressures below 0.3 GPa, andalusite is the stable aluminum silicate. Gemstone-quality kyanites are found in India, in gemstone deposits in Myanmar, and Korea. In the United States, kyanites are mined in California, Tennessee, Georgia, New Hampshire, and North Carolina. In Africa, kyanite occurs in Kenya and Tanzania; in Europe, in Russia, Switzerland, Austria, and France. Kyanite occurs in the sand fraction of Dutch Quaternary river sediments. In heavy mineral analysis conducted in the Netherlands by the National Geological Survey during the second half of the twentieth century, the mineral is classified in the so-called stable group. In this study, only the name disthene is used.
Aquamarine (Latin: aqua marina, "seawater") is a fairly precious gemstone and a variety of the mineral beryl. Its color is pale green, yellow-green, pale blue, or blue-green. Aquamarine is a common mineral and, like other beryllium-bearing minerals, occurs primarily in pegmatites. Its deposits include Brazil (Minas Gerais), Madagascar, the Urals, Nigeria, Pakistan, Mexico, India, Ireland, Zimbabwe, Afghanistan, and the United States. Aquamarine Types: Santa Maria - A quality designation for very good aquamarines. Named after the mine of the same name in Ceará, Brazil. Santa Maria Africana - A quality designation for good aquamarines from Mozambique, marketed since 1991. The name is derived from the 'Santa Maria' quality from Ceará, Brazil. Maxixe Aquamarine - A dark blue aquamarine. The color fades in daylight. Originally from the Maxixe mine in Minas Gerais, Brazil. Regularly offered since the 1970s, it has apparently been irradiated. The color is not colorfast. In the Middle Ages, statues of the Virgin Mary were adorned with aquamarine. Legend has it that the stone belonged to a mermaid and leads to love. It warns of injustice when the stone discolors. Some naturopaths attribute several medicinal properties to aquamarine, namely strengthening the immune system, combating seasickness and skin allergies, and promoting peace and relaxation. Astrologers have differing views on the zodiac signs associated with aquamarine, which are Aquarius, Libra, Pisces, Aries, and Gemini.
Tourmaline and the mines.
