Sillimanite was discovered in the year 1824 and get its name from an American professor of chemistry and geology, Mr. Benjamin Silliman. Sillimanite is a very rare trimorph and it has a common variety called fibrolite.
Sillimanite
Click Here for Techinical Specification
Sillimanite is formed from aluminum silicate and is a transparent to translucent mineral ranging from white to gray, brown and green.
SILLIMANITE
Overview: It was named after the American chemist and mineralogist, Professor Benjamin Silliman (1779-1824). Sometimes referred to as "Fibrolite", the crystals occur in groups, resembling fibers.
Sillimanite is typically found scattered within layers of metamorphic rocks that have been put under great pressure and high temperature. This is why sillimanite is commonly found in volcanic or hot spring areas.
SILLIMANITE
Sillimanite (aluminum silicate, Al2 SiO5) is a transparent to translucent mineral that ranges in color from white to gray to brownish to greenish.
Sillimanite
Nice sharp eye and well-centered on near colorless body. Good transparency.
Weight: 18.15 carats
Size: 15.13 x 11.76 x 8.57 mm
Cut: Oval
Enhancements: None
Price: $1,089 total
Ask for inventory #11451 ...
Sillimanite"Indicator mineral for high grades of metamorphism.
Sphalerite"The major zinc ore and an interesting mineral.
Spinel"Rugged oxide mineral of metamorphosed limestones.
SLM120, Sillimanite, Fibrolite, [N], 12.2mm Cabochon, Round Cut, 5.52 ct. $ 69.99
SLM121, Sillimanite, Fibrolite, [N], 10.9x11.2mm Cabochon, Round Cut, 9.12 ct. $ 114.99 ...
See Kyanite, Sillimanite.^M
Varieties: Chiastolite, Viridine
Al2SiO5
Crystallography: orthorhombic
Colors: green, greenish brown w/ reddish tints chiastolite is impure variety showing gray cross on black or gray ground.
Hardness: 7.5 ...
This aluminum silicate is a polymorph with andalusite and sillimanite, meaning it shares the same chemistry but a different crystal structure with these other minerals.
My previous article initiated a series on polymorphic aluminum silicate gemstones, beginning with andalusite, following with kyanite (disthene) and ending with sillimanite (fibrolite).
Gemstone Physical Composition: Kyanite is a polymorph with two other minerals: andalusite and sillimanite. A polymorph is a mineral that shares the same chemistry but a different crystal structure with another, or other, minerals.
Kyanite's name is derived from the Greek word kyanos, meaning blue, is a polymorph with two other minerals; andalusite and sillimanite.
A polymorph with two other minerals, Kyanite and Sillimanite, Andalusite is an aluminum silicate. It is pleochroic, which means it displays all its different orange, brown, yellow, green and golden colours in different directions at the same time.
The name, Andalusite, comes from the Spanish local Andalusia. It is one of three polymorphs of Aluminum Silicate, the other two being Sillimanite, and Kyanite. They are related through their pressure and temperature of formation.
kyanite, sillimanite and Andalusite. All three are related to each other with respect to their pressure and temperature formation. These are found rarely and produced in limited quantity even when so many countries produce it.
Andalusite
Faceted andalusite stones give a play of red, green, and yellow colors that resembles a muted form of iridescence. Andalusite belongs to the same family as kyanite and sillimanite.
minerals are encountered with combinations of the various forms presented so far. These include andalusite, the members of the aragonite and barite group, brookite, chrysoberyl, the orthopyroxenes, goethite, marcasite, olivine, sillimanite, stibnite, ...
This is usually related to the metamorphic temperatures of pelitic or alumonisilicate rocks and the minerals they form. The metamorphic grades of aureoles are andalusite hornfels, sillimanite hornfels, pyroxene hornfels.
forms elongated columnar crystals known as "blades," which are heavily striated lengthwise along the c-axis. Kyanite typically occurs in association with, or is a polymorph of several other silicate minerals such as andalusite, micas, sillimanite, ...
reflection centered on the cabochon dome is formed which is referred to as a cat'seye. Many gem species have cat'seye varieties, including (but not limited to ) apatite, actinolite, beryl, chrysoberyl, Kornerupine, tourmaline, quartz, sillimanite, ...
It has a specific gravity of 3.58. Kyanite is found in Brazil, Burma, Kenya, Europe, India, Australia, Kenya, and the USA. Kyanite's chemical composition is Al2SiO5; it is composed of andalusite and sillimanite.
Minerals characteristic of low- grade metamorphic environments include the zeolites, chlorites, and andalusite. Minerals character istic of high grade metamorphic environments include sillimanite, kyanite, staurolite, epidote, and amphiboles.
 See also: Crystal, Stone, Mineral, Gemstone, Andalusite
  
|
RSS
