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GEMS-022 - Sillimanite - $ 200 Sri Lanka thumbnail, 8.6 x 5.0 mm ; 1.03 carats
Sillimanite is sometimes called "Fibrolite" because of the fibrous nature of the material. This is actually pretty rare material, and considering the clarity and color of this particular stone, it's a significant gem. In my experience Sillimanite stones are often very pale in color, almost appearing colorless. Most gems you see on the market are some light shade of blue, green or purple. This stone has a great greenish-yellow color with an "Oval Brilliant" cut and it is only very slightly included.
K302 - Sillimanite (huge gem xl) - $ 2000 Orissa, India thumbnail, 2.7 x 2.1 x 0.9 cm ex. Charlie Key
Charlie was very impressed with this rare gem crystal of sillimanite, which he told me was the best he had seen, for combination of size and form. I cannot argue, as I have never seen but rounded pebbles of this material, from Mogok and not from India. The crystal is a little bit like a floppy wizards hat in form, but it is translucent and 3-dimensional, and actually displays quite well. I am inclined to fully trust Charlie about its significance in the absence of anything to compare it to out there.
MD-112916 - Sillimanite - - Archived Orissa, India thumbnail, 2.7 x 2.1 x 0.9 cm
Charlie was very impressed with this rare gem crystal of sillimanite, which he told me was the best he had seen, for combination of size and form. I cannot argue, as I have never seen but rounded pebbles of this material, from Mogok and not from India. The crystal is a little bit like a floppy wizards hat in form, but it is translucent and 3-dimensional, and actually displays quite well. I am inclined to fully trust Charlie about its significance in the absence of anything to compare it to out there. 2.7 x 2.1 x 0.9 cm
MD-199671 - Sillimanite - - Archived Yantic Falls, Norwich, New London Co., Connecticut, USA cabinet, 11.4 x 6.2 x 4.6 cm.
11.4 x 6.2 x 4.6 cm. Flat-lying, lustrous crystals of sillimanite (to 3 cm) embedded in schist matrix, a rich specimen from a historic old locality. Ex. Philadelphia Academy of Sciences Collection.
MD-199678 - Sillimanite - - Archived Chester, Middlesex Co., Connecticut, USA cabinet, 12.4 x 7.1 x 2.7 cm.
12.4 x 7.1 x 2.7 cm. A large specimen of the mineral sillimanite, named surely near the time this was found after Professor Silliman of Yale, with 3-dimensional but embedded crystals. Ex. Charles Shepherd Collection (1804-1886), whom according to the Mineralogical Record Archive on him was with Benjamin Silliman's staff at Yale in 1827, as his assistant, and later as a lecturer on natural history at Yale (1830-1847) and then Amherst College. His large collection was donated to the Smithsonian, but a few specimens apparently found their way into the Academy collection, perhaps through trades with colleagues in the Philadelphia area. Ex. Philadelphia Academy of Sciences Collection.
MD-199870 - Monazite-(Ce), Sillimanite - - Archived Yantic Falls, Norwich, New London Co., Connecticut, USA small cabinet, 8.1 x 6.0 x 2.8 cm.
8.1 x 6.0 x 2.8 cm. A rare locality piece of monazite-(Ce), in sillimanite. The sharp crystal noted is 5 or 6mm and fully crystallized. Ex. Samuel Ashmead Collection.
MD-211590 - Sillimanite - - Archived Mogok, Sagaing District, Mandalay Division, Burma (Myanmar) thumbnail, 1.7 x 0.9 x 0.3 cm.
1.7 x 0.9 x 0.3 cm. Sillimanite is a high temperature and high pressure aluminum silicate found in high-grade regional metamorphic rocks. Transparent crystals are called "fibrolite" by gemologists. This is a gemmy, fine, light purple elongate crystal with a bit of rounding. The edge rounding likely represents resorption into the matrix more than stream wear. This example from Mogok, Burma is sharper than most. Ex. Irv Brown Collection. 5.06 carats.
MD-21347 - Sillimanite - - Archived Ratnapura, Ratnapura District, Sabaragamuwa Province, Sri Lanka thumbnail, 3 x 0.6 x 0.4 cm
The first of three remarkable crystals of this usually-boring species, brought back from Sri Lanka personally by a friend of mine about 15 years ago. This doubly-terminated crystal is partially etched, but clearly shows both terminations 3 x 0.6 x 0.4 cm
MD-231845 - Sillimanite - - Archived Mogok, Sagaing District, Mandalay Division, Burma (Myanmar) thumbnail, 1.8 x 0.9 x 0.4 cm.
1.8 x 0.9 x 0.4 cm. Sillimanite is a high temperature and high pressure aluminum silicate found in high-grade regional metamorphic rocks. Transparent crystals are called "fibrolite" by gemologists. This is a gemmy, fine, lavender, elongate crystal with a bit of rounding. The edge rounding likely represents resorption into the matrix more than stream wear. This example from Mogok, Burma is sharper than most. 7.22 carats.
MD-278397 - Sillimanite - - Archived Oconee Co., South Carolina, USA thumbnail, 3.0 x 2.4 x 1.3 cm.
3.0 x 2.4 x 1.3 cm. Sillimanite is a high temperature and high pressure aluminum silicate found in high-grade regional metamorphic rocks. Lustrous, parallel-growth, olive-brown sillimanite crystals are embedded in schist matrix on this fine and rich toenail specimen from a very uncommon South Carolina locality. Seldom available in any size from this locale. Ex. Carlton Davis Collection.
MD-83126 - Sillimanite - - Archived Mogok, Sagaing District, Mandalay Division, Burma (Myanmar) thumbnail, 2.2 x 0.7 x 0.5 cm
2.2 x 0.7 x 0.5 cm
PAS-18 - Sillimanite - $ 200 SOLD Yantic Falls, Norwich, New London Co., Connecticut, USA cabinet, 11.4 x 6.2 x 4.6 cm ex. Philadelphia Academy of Natural Sciences
Flatlaying, lustrous crystals of sillimanite (to 3 cm) embedded in schist matrix, a rich specimen from a historic old locality.
PAS-20 - Sillimanite - $ 300 SOLD Chester, Middlesex Co., Connecticut (TYPE LOCALITY) cabinet, 12.4 x 7.1 x 2.7 cm ex. Philadelphia Academy of Natural Sciences
Another large specimen of the mineral sillimanite, named surely near the time this was found after Professor Silliman of Yale, with more 3-dimensional but embedded crystals. An interesting historic example probably from the type locality. ex.Charles Shepherd Collection (1804-1886), whom according to the Mineralogical Record Archive on him was with Benjamin Silliman's staff at Yale in 1827, as his assistant, and later as a lecturer on natural history at Yale (1830-1847) and then Amherst College. His large collection was donated to the SMithsonian, but afew specimens apparently found their way into the Academy collection, perhaps through trades with colleagues in the Philadelphia area.
PAS-39 - Monazite-(Ce) in Sillimanite - $ 100 SOLD Yantic Falls, Norwich, New London Co., Connecticut, USA small cabinet, 8.1 x 6.0 x 2.8 cm ex. Philadelphia Academy of Natural Sciences
A rare locality piece of monazite, in sillimanite. The sharp crystal noted is 5 or 6mm and fully crystallized. From the noted colletion of Samuel Ashmead.
RLKG10-194 - Sillimanite Cat's Eye - $ 600 India thumbnail, 9.0 x 8.6 mm ; 4.87 carats
Sillimanite is actually trimorphous with Kyanite and Andalusite which means that they have the same chemistry, but different crystal habits create different minerals, just like Brookite, Anatase and Rutile. Sillimanite is sometimes called "Fibrolite" because of the fibrous nature of the material. This is actually pretty rare material, and one of the few I've seen in this color. This stone has a very distinct "eye" and a really unusual "smoky" purple color. The stone has good clarity as well. I photographed this stone with a strong penlight shining right on the stone to show the "eye" better, so it might not be as disticnt depending on what lighting in which you're viewing the stone.
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