Tektite Value, Price, and Jewelry Information

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In 1996, this piece on display at the Egyptian Museum of Cairo caught the eye of a mineralogist. As it turned out, the yellow-green gem in the middle of this pectoral of King Tutankhamun’s (1332–1323 BCE) was Libyan desert glass, a variety of tektite. Photo by RolandUnger. Licensed under CC By-SA 3.0. (Cropped to show detail).

Tektite is a natural glass formed from the ejected debris of meteorite impacts. Though most pieces are very small, some tektite varieties have been cut and used for jewelry since prehistoric times.

Tektite Value

The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.

Tektites are popular as “raw stones” for jewelry or as display pieces. The value of these rough specimens depends greatly on their shape, size, and visual appeal.

Tektites large enough to be cut into gemstones are rare. The value of cut tektites depends mostly on their size, transparency, color, and cut quality. Most tektites are opaque and have dark colors. Thus, translucent and lighter gems tend to sell for higher prices. However, opaque and dark gemstones also have their aficionados.

This gentleman’s 18k gold ring features an inverted, oval-shaped tektite (16.30 x 13.95 x 10.35 mm) accented by inverted, square-shaped rubies. Photo courtesy of liveauctioneers.com and Heritage Auctions.

Although very rare, moldavites are the tektite variety most likely to be sold as gemstones. They’ll likely command the highest prices of all tektites, though they’re still relatively inexpensive.

Tektite Information

Data	Value
Name	Tektite
Varieties	Australite, Bikolite, Billitonite, Darwin Glass, Moldavite
Formula	Silica (75%) + Al, Fe, Ca, Na, K, Mg, Ti, Mn.
Colors	Black, green, yellowish green, greenish brown, brown, colorless.
Fracture	Conchoidal
Hardness	5-6.5
Cleavage	None
Crystallography	Amorphous (tektites are natural glasses).
Refractive Index	1.46-1.54
Birefringence	None
Luminescence	None in UV. Yellow-green in X-rays.
Luminescence Present	Yes
Luminescence Type	X-ray Colors
Absorption Spectrum	Moldavites may show two vague bands in the blue and orange range.
Pleochroism	None
Optics	Isotropic; N = 1.46-1.54.
Luster	Vitreous
Specific Gravity	2.21-3.40 (see table)
Transparency	Transparent to opaque
Etymology	From the Greek tektos for “molten.” Varieties are named after the localities where they occur.
Occurrence	All tektites occur in the strewn fields of meteorite impacts, where the gems are literally strewn over the ground in a very wide area.
Inclusions	Numerous rounded or torpedo-shaped bubbles (common); also swirl striae that are unlike those seen in paste (glass used to imitate gemstones).

Tektite (moldavite), Czech Republic (6.4). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Are Tektites Meteorites?

Scientists have proposed different theories about the origins of tektites. For example, it has been argued that tektites formed from an explosive event on the Moon and were thrown all the way to the Earth’s surface. However, current scientific consensus holds that tektites formed from the impact of meteorites on the Earth’s surface. Material from the Earth, melted on impact, was ejected into the atmosphere, then fell back to the surface and cooled into tektites.

Unlike stony, iron, and stony-iron meteorites recovered on Earth, tektites have terrestrial origins. Although formed by meteorite impacts, the tektites themselves have never been in outer space. The composition of tektites is consistent with terrestrial materials.

Philippinite (rizalite), 3 x 2 x 1 cm, 10 g, Paracale, Camarines Norte, Luzon, Philippines. Photo courtesy of liveauctioneers.com and Jasper52.

Tektite Varieties and Sources

The following table contains information on tektites most likely of interest to gemologists and jewelers.

The refractive indices (RI) of tektites seem to vary (positively) with iron content.

Name	Locality	Largest Known Size	Specific Gravity	Refractive Index	Color
Moldavite*	Czech Republic (also Austria, Germany, Poland)	235 grams	2.27-3.40	1.48-1.54	bottle green, yellowish green, brown-green
Australite*	Australia	218 grams	2.38-2.46	1.50-1.52	black, brown edge
Darwin glass	Tasmania	–	2.75-2.96	1.47-1.48	green, black
Javaite	Java	–	2.43-2.45	1.509	black
Billitonite	Billiton Island (near Borneo)	–	2.46-2.51	1.51-1.53	black
Indochinite*	Cambodia, Southern China, Laos, Thailand, Vietnam	3200 grams	2.40-2.44	1.49-1.51	black
Philippinite (Rizalite)	Philippines, especially Luzon	–	2.44-2.45	1.513	black
Ivorite	Ivory Coast	–	2.40-2.51	1.50-1.52	black
Libyan Desert Glass*	Egypt, Libya	4500 grams	2.21	1.462	pale greenish yellow
Bediasite*	Gonzales County, Texas	91.3 grams	2.33-2.43	1.48-1.51	black
Georgiaite*	Georgia	–	2.33	1.485	light olive-green
Massachusetts tektite*	Martha’s Vineyard, Massachusetts	–	2.33	1.485	light olive-green

* Lapidaries have faceted this material.

A translucent georgiaite, found in Dodge County, Georgia. Photo by Megan.ruffin1. Licensed under CC By-SA 4.0.

Distinguishing Tektites from Other Glass Varieties

Vendors may sell manufactured glass pieces as natural tektites, particularly moldavites. (Of course, these are the most well-known variety and most likely to appear in jewelry or as cut gems). Examining inclusions and testing for fluorescence are the easiest ways to begin identifying them. See the moldavite gem listing for more information.

Tektites may be confused with another variety of natural glass: obsidian. While tektite is rare, obsidian is very common, which may lead to some misidentifications. This volcanic rock has many properties that overlap with those of tektite: color, hardness, specific gravity, and RI.

Analyzing obsidian and other natural glasses with an Ultraviolet-visible-Near Infra-Red spectroscope (UV-vis-NIR) will show sharp bands at 1380 and 2210–2250 nm, which indicate the presence of water. Tektites won’t have these bands because they contain virtually no water.

This near total absence of water makes possible another, more dramatic, way to distinguish tektites from obsidians. Jim Tobin explains this procedure in his 2003 article on tektite testing. When gently heated with an oxy-acetylene flame, obsidians will froth and become pumice. In contrast, tektites won’t froth. However, after cooling down, they’ll invariably shatter within a few hours due to thermal stress. (Obviously, this test isn’t recommended for finished gems).

Tektite Sizes

Lapidaries have faceted moldavite gems weighing up to 25 cts. Other, more rarely faceted tektites are typically much smaller, although large pieces of rough indochinite and Libyan desert glass have been found.

An unusually large, pear-cut indochinite, 8.4 x 22 x15 mm, 12.75 cts, Laos. Photo courtesy of liveauctioneers.com and Jasper52.

Caring for Tektite Jewelry

Tektites range in hardness from 5 to 6.5, which makes them susceptible to scratching. (Household dust, with a hardness of 7, would easily scratch their surfaces). As ring stones, they should receive protective settings and only occasional wear. However, other jewelry uses, such pendants and earrings, should present no problems.

Since tektites can contain numerous inclusions, don’t use steam or ultrasonic systems to clean them. Instead, use a soft brush, mild detergent, and warm water. Consult our gemstone jewelry cleaning guide for more recommendations.