Forsteriitti / forsterite
Alkuperä (todennäköinen) : Burma
Paino ( ct noin ) :0.75
Mitat ( mm noin ) : 5,5 x 4,5 x 3,8
Hionta : viistehiottu
Puhtaus : SI1
Erinomainen Erittäin hyvä Hyvä kakkosluokkaa”
Ominaista : kirkas väritön Burmalainen forsteriitti
Forsterite is named for the German naturalist, Johann Forster. It is one of two minerals that form an isomorphous series within the olivine group. The other mineral is fayalite. Fayalite is the iron rich member with a pure formula of Fe2SiO4 while forsterite is the magnesium rich member with a pure formula of Mg2SiO4. Forsterite's gemstone variety is known as peridot.
|Color Key:||Light green yellow to the more common yellowish green; also known to be colorless.|
|Refractive Index::||1.64 - 1.71|
|Hardness:||6.5 - 7|
|Ocurrence:||Zagbargad (Zebirget) Island in the Red Sea off the coast of Egypt and Mogok, Myanmar (formerly known as Burma). The type locality is Mt. Vesuvius, Italy and other localities include Kohistan, Pakistan; South Africa; Ural Mountains, Russia; Norway; Sweden; France; Minas Gerais, Brazil; Eifel, Germany; Chihuahua, Mexico; Ethiopia; Mt. Franklin, Victoria, Australia; Notre-Dame-du-Laus, Quebec Canada; China and Salt Lake Crater, Oahu, Hawaii; North Carolina; Bolton, Massachusetts; Crestmore, California; New Mexico and the most productive source of peridot to date from Peridot Mesa, San Carlos Apache Reservation, Gila County, Arizona, USA.|
|Forsterite is found in igneous rocks or in marbles made from the metamorphism of dolomitic limestones. Forsterite is never found with quartz, SiO2, as these two common minerals are unstable in each others proximity during crystallization. If quartz were present, the two would react and form the mineral enstatite. |
Forsterite is also found in many iron-nickel meteorites. Not just as small grains but as significantly sized crystals sometimes occupying over 50% of the meteorites volume. Thinly cut slices of these meteorites are extremely attractive with the polished steel gray of the iron and the embedded grains of gemmy green forsterite crystals. The effect produces a close mineral equivalent to stained glass artwork.