IOLITE, the gemstone variety of cordierite

VARIETY INFORMATION:

  • VARIETY OF: Cordierite, Mg2Al4Si5O18, Magnesium Aluminum Silicate.
  • USES: Gemstone
  • COLOR: Various shades of yellowish gray to blue to a blue violet, deeper along the crystal axis.
  • INDEX OF REFRACTION: 1.52 - 1.57
  • BIREFRINGENCE: is good
  • HARDNESS: 7 - 7.5
  • CLEAVAGE: poor in one direction
  • CRYSTAL SYSTEM: orthorhombic
  • We have natural Iolite Mineral Specimens
    For Iolite Jewelry, see --> IOLITE JEWELRY

Iolite is a popular and interesting gemstone, and is the gem variety of the mineral cordierite. It has a delicate and quite pretty violet blue color that is unlike other gemstones, although it has been compared to a light blue sapphire. It is this reason that it is sometimes known as "water sapphire". Although the color is attractive and popular, iolite is not extremely rare and is therefore affordable.

Pleochroism is very pronounced in iolite and is seen as three different color shades in the same stone. In the viewing an iolite stone, the colors violet blue, yellow gray and a light blue can be seen, all a result of pleochroism. Tanzanite is a blue-violet gemstone variety of the mineral zoisite, has strong pleochroism as well and can be easily confused with iolite. However, tanzanite is usually more strongly colored, its pleochroic colors vary from dark blue, green-yellow and red-purple and it has greater fire.

The major sources of gem grade iolite come from Sri Lanka, India, Madagascar and Burma.

IOLITE specimens:
(hover for more info)
IOLITE specimen iol-1
$ 91.00
Dims: 1.0 x 0.8 x 0.5" (2.5 x 2.0 x 1.3 cm)
Wt: 9.1 g
Zambia
A rounded, broken chunk of Iolite comprises this thumbnail specimen. It shows no crystal form (we have yet to see an actual Iolite crystal), and all edges are rough and uneven, often showing a conchoidal fracture. The material has wonderful coloration, however, and shows obvious pleochroism: from some angles, it has a rich, golden color with a hint of orange, from others it is violet with a hint of blue, and at still others, its violet color is so deep as to be nearly opaque. The material is transparent and appears to be quite clear, though the piece may contain a few internal fractures. There is no host rock attached.
no photo
iol-1 ($ 91.00)
Zambia
IOLITE specimen iol-2
$ 74.00
Dims: 1.0 x 0.7 x 0.6" (2.5 x 1.8 x 1.5 cm)
Wt: 7.4 g
Zambia
This thumbnail specimen consists of a small, misshapen chunk of Iolite. Though it appears to show part of a crystal face, it is otherwise rough and uneven, showing many conchoidal surfaces. Fresh damage is denoted with a bright, vitreous luster, whereas older damage is duller. Though it appears to contain a few internal fractures, the interior of the piece is transparent and quite clear. It shows obious pleochroism, and its color ranges from a rich golden to a moderate blue-violet to a deep violet. There is no host rock present. (Sold to Anders G.)
no photo
iol-2 ($ 74.00)
Zambia
IOLITE specimen iol-3
$ 31.00
Dims: 0.7 x 0.5 x 0.3" (1.8 x 1.3 x 0.8 cm)
Wt: 3.1 g
Zambia
This small, shapeless Iolite piece has a rough surface that possesses a pearly-to-vitreous luster. Its pleochroism is standard for its species- its color ranges from a pale golden to a blue-violet to a deep violet. The piece is transparent and quite clear, though there do appear to be a few roughly parallel internal fractures.
no photo
iol-3 ($ 31.00)
Zambia
IOLITE specimen iol-4
$ 30.00
Dims: 0.5 x 0.4 x 0.4" (1.3 x 1.0 x 1.0 cm)
Wt: 2.3 g
Zambia
This small Iolite piece shows no appreciable crystal form and what appears to be some fresh breakage. It has the standard pleochroism of its species- its color ranges from a deep violet to a moderate blue-violet to a pale, dull gold. It is transparent and appears to be very clear, containing few inclusions or flaws, if any.
no photo
iol-4 ($ 30.00)
Zambia
IOLITE specimen iol-5
$ 25.00
Dims: 0.5 x 0.5 x 0.3" (1.3 x 1.3 x 0.8 cm)
Wt: 1.6 g
Zambia
This small, rough Iolite chunk would make a good stone on which to practice faceting. It shows no visible crystal form but has good pleochroism, showing violet, blue-violet and dull golden colors depending on the angle from which it is viewed. It is transparent and quite clear, though it does appear to contain a few internal fractures near its surface.
no photo
iol-5 ($ 25.00)
Zambia
IOLITE specimen iol-6
$ 25.00
Dims: 0.6 x 0.5 x 0.4" (1.5 x 1.3 x 1.0 cm)
Wt: 1.5 g
Zambia
This small thumbnail specimen consists of a single, shapeless piece of Iolite. Its rough surfaces have a pearly luster and its color ranges from a pale gold to a dull violet. It is transparent and moderately clear, containing some internal fractures and possibly a few inclusions.
no photo
iol-6 ($ 25.00)
Zambia
IOLITE specimen iol-7
$ 70.00
Dims: 0.9 x 0.7 x 0.3" (2.3 x 1.7 x 0.7 cm)
Wt: 3 g
unknown
A misshapen piece of Iolite makes up this thumbnail specimen. There is no visible crystal shape, and though fresh damage is visible, revealing its vitreous luster, most of its surfaces are weathered and pearly. Its color ranges from a pale blue violet to a deep violet to a pale beige, depending on the angle from which it is viewed. The piece is transparent and rather clear, though it does contain a few large internal fractures. There is no host rock present.
no photo
iol-7 ($ 70.00)
unknown
IOLITE specimen iol-8
$ 70.00
Dims: 0.6 x 0.4 x 0.2" (1.6 x 1.1 x 0.4 cm)
Wt: 1 g
not yet determined
This small thumbnail specimen might possibly be a warped, damaged crystal, but is more likely a shard that has undergone some weathering. The piece shows considerable fresh damage along its edges, denoted by a vitreous luster, but the weathered areas are pearly. It has excellent violet color that deepens along two axes and fades to a pale beige along two other axes. It is transparent and very clear, containing only one or two internal fractures or inclusions. There is no host rock present, and it is affixed inside a plastic thumbnail box with a removable putty.
no photo
iol-8 ($ 70.00)
not yet determined
IOLITE specimen iol-10
$ 50.00
Dims: 0.6 x 0.5 x 0.2" (1.6 x 1.2 x 0.5 cm)
Wt: 1-2 g
unknown
This small thumbnail specimen consists of a shapeless chunk of Iolite. It shows no visible crystal form and all of its surfaces show the curvature of conchoidal fracture. It appears to have been heat-treated, as it shows no pale brown color when viewed from any angle- the only pleochroic colors that are visible are a pale blue-violet and a deep violet. The piece is transparent and quite clear, however. No host rock is present, and the specimen is affixed inside a plastic specimen box with a removable putty.
no photo
iol-10 ($ 50.00)
unknown
IOLITE specimen iol-9
$ 70.00
Dims: 1.1 x 0.5 x 0.2" (2.7 x 1.2 x 0.5 cm)
Wt: 2 g
unknown
This Iolite crystal shard appears to have no fresh damage- it was broken and either weathered or partly healed before it was mined. It was likely healed over slightly, as its surfaces seem to have almost crystalline patterns. It has a dull, pearly luster and the classic trichroic coloration- its color is blue-violet, deep violet, or a dull, violet-beige, depending on the angle from which it is viewed. It is transparent and quite clear. There is no host rock present, and the piece is affixed inside a plastic specimen box with a removable putty.
no photo
iol-9 ($ 70.00)
unknown
IOLITE specimen iol-11
$ 45.00
Dims: 0.6 x 0.4 x 0.2" (1.6 x 1.1 x 0.5 cm)
Wt: 2 g
unknown
A small, misshapen piece of Iolite comprises this thumbnail specimen. It shows no crystal form, and all surfaces are chonchoidally curved. When viewing from various angles, one can see beige, pale blue-violet and deep violet colors. The piece is transparent and very clear, and shows a vitreous luster. It is affixed inside a plastic specimen box with a removable putty.
no photo
iol-11 ($ 45.00)
unknown
IOLITE specimen iol-13
$ 35.00
Dims: 0.8 x 0.6 x 0.2" (2.0 x 1.5 x 0.5 cm)
Wt: 1 g
unknown
A small, shapeless chunk of Iolite makes up this small thumbnail specimen. It exhibits no crystal form and shows both old and fresh damage with conchoidal surfaces. Its color ranges from deep violet to blue-violet to a pale brown-yellow, and its luster ranges from a dull pearly on the old damage to vitreous on the fresh. It is transparent and quite clear, and is not attached to any base or host material. The piece is affixed inside a thumbnail box with a removable putty.
no photo
iol-13 ($ 35.00)
unknown
IOLITE specimen iol-12
$ 35.00
Dims: 0.6 x 0.6 x 0.2" (1.5 x 1.4 x 0.5 cm)
Wt: 2 g
unknown
This small piece of Iolite has what might actually be some discernable crystal form, though it is rather heavily worn and was likely damaged and then healed over or worn down. Its pleochroic color shows the standard deep violet, pale blue-violet and pale beige colors, and its luster is waxy. The piece is transparent and quite clear, and is affixed inside a thumbnail box with a removable putty.
no photo
iol-12 ($ 35.00)
unknown
IOLITE specimen iol-14
$ 25.00
Dims: 0.7 x 0.4 x 0.2" (1.7 x 1.0 x 0.5 cm)
Wt: 1 g
unknown
This small thumbnail piece consists of a shapeless chunk of Iolite. It shows considerable fresh damage and no evidence of crystal form. Its pleochroism is standard for the specie, alternating between blue-violet, deep violet and pale beige colors. Where its damage is fresh, it shows a vitreous luster- otherwise, its luster is pearly. It is affixed inside a thumbnail box with a removable putty.
no photo
iol-14 ($ 25.00)
unknown
IOLITE specimen iol-15
$ 120.00
Dims: 0.8 x 0.7 x 0.6" (2.0 x 1.7 x 1.4 cm)
Wt: 5 g
unknown
Though essentially formless, this Iolite specimen might actually show evidence of crystal form! Many of the surfaces are conchoidal and uneven, but a few suggest some definable structure. The piece has the standard pleochroism, showing deep violet, pale blue-violet and pale beige colors. Surfaces with fresh damage have a vitreous luster, while older damage and other surfaces are more pearly. The Iolite is transparent and quite clear, and the piece is affixed inside a thumbnail box with a removable putty.
no photo
iol-15 ($120.00)
unknown
IOLITE specimen iol-16
$ 25.00
Dims: 0.65x0.27x0.22" (1.66x0.68x0.55cm)
Wt: 3.20ct (0.64g)
Espirito Santo, Brazil
This is a fragment of an iolite crystal. It shows only fracture surfaces, with no crystal faces. While this crystal is rather pale, it does show excellent pleochroism, appearing yellowish, violet, and blue from different angles.
no photo
iol-16 ($ 25.00)
Espirito Santo, Brazil
IOLITE specimen iol-17
$ 25.00
Dims: 0.40x0.41x0.30" (1.01x1.03x0.75cm)
Wt: 3.80ct (0.76g)
Espirito Santo, Brazil
This is a fragment of an iolite crystal. One surface appears natural (although it may simply be the attachment point), and the remaining surfaces are all fracture. The crystal is transparent, vitreous, and shows excellent pleochroism, appearing violet, pale gray, or pale yellow depending upon the viewing angle. This is a gem-quality shard - a high-quality gem could be cut from it.
no photo
iol-17 ($ 25.00)
Espirito Santo, Brazil
IOLITE specimen iol-18
$ 25.00
Dims: 0.54x0.35x0.29" (1.37x0.88x0.74cm)
Wt: 4.0ct (0.80g)
Espirito Santo, Brazil
This is another shard of iolite. All surfaces are fracture surfaces, and there is no indication of crystal form, other than the pleochroism, which is excellent, and indicates the crystal axis directions. The iolite crystal appears blue in some directions, yellow in another, and a pale gray-blue in a third. Actually, the pleochroism indicates that this is two intergrown crystals, as a small part of one side has a different color play. It is yellow when the bulk of the specimen appears blue, although this may be due to a differing composition, as this small portion of the specimen appears yellow from most angles.
no photo
iol-18 ($ 25.00)
Espirito Santo, Brazil
IOLITE specimen iol-19
$ 25.00
Dims: 0.42x0.34x0.29" (1.06x0.86x0.73cm)
Wt: 4.0ct (0.80g)
Espirito Santo, Brazil
This is a shard of iolite, with no natural crystal surfaces, only fractures. The only indication of crystal form is this specimen's pleochroism, which is quite good. From some angles, it appears blue, and from others a pale yellow-gray. The iolite appears transparent, although the rough surface texture precludes an examination of the interior.
no photo
iol-19 ($ 25.00)
Espirito Santo, Brazil
IOLITE specimen iol-20
$ 25.00
Dims: 0.46x0.38x0.26" (1.18x0.96x0.65cm)
Wt: 3.5ct (0.7g)
Espirito Santo, Brazil
This is a shard (fragment) of an iolite crystal. There is no indication of crystal form, other than the well-defined pleochroism which identifies the crystal axes. The surface is all fractures, and thus is rough and hides the transparency of the iolite, which I believe is excellent. The pleochroism is strong, violet in one direction, pale yellow in another, and a faint gray-violet in a third.
no photo
iol-20 ($ 25.00)
Espirito Santo, Brazil

 


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