Tektite Value, Price, and Jewelry Information

TEKTITE: Moldavite, Czechoslovakia (6.4). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Tektite

Tektites were first discovered in 1787 in Czechoslovakia (then Moravia) near the River Moldau, hence the name moldavite. It has been argued that tektites originated as a result of violent explosive activity on the Moon and were thrown all the way to the Earth’s surface. Other scientists, currently in the majority, argue that tektites are of terrestrial origin. The issue is being debated in a lively way.

Tektite Information

Data Value
Name Tektite
Varieties Australite, Bikolite, Billitonite, Darwin Glass, Moldavite
Colors Black, green, greenish brown, brown in moldavites; other tektites black, colorless to brown.
Crystallography Amorphous (tektites are natural glasses).
Refractive Index 1.46-1.54
Luster Vitreous.
Hardness 5.5-6.5
Fracture Conchoidal
Specific Gravity 2.21-3.40 (see table).
Birefringence None.
Cleavage None
Stone Sizes Faceted gems are usually cut from moldavites because the color of these tektites is lighter than most others. The color is a bottle green resembling diopside, and gems up to about 25 carats have been cut, although very large moldavites have been found. Various other tektites from the United States have been cut as curiosities, mostly small. The refractive index of a tektite seems to vary (positively) with iron content.
Luminescence None in UV. Yellow-green in X-rays.
Luminescence Present Yes
Luminescence Type X-ray Colors
Transparency Transparent to opaque.
Absorption Spectrum Not diagnostic. Moldavites may show two vague bands in the blue and orange.
Formula

Silica (75%) + Al, Fe, Ca, Na, K, Mg, Ti, Mn.
Pleochroism

None.
Optics

Isotropic; N = 1.46-1.54.

Optics: Isotropic; N: 1.46-1.54.

Inclusions: Often see numerous rounded or torpedo-shaped bubbles; also swirl striae that are unlike those seen in paste (glass used to imitate gemstones).

Occurrence: Tektites occur worldwide in fields in which the glass bits are literally strewn over the ground, covering a very wide area (see table).

Name

Locality

Maximum Size

Specific Gravity

Refractive Index

Color
Moldavite*

Czechoslovakia

235 grams

2.27-3.40

1.48-1.54

bottle 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*

Indochina

3200 grams

2.40-2.44

1.49-1.51

black
Philippinite (rizalite)

Philippines, especially Luzon

–

2.44-2.45

1.513

black
Ivory Coast tektite

Ivory Coast

–

2.40-2.51

1.50-1.52

black
Libyan Desert Glass*

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
Georgia tektite*

Georgia

–

2.33

1.485

light olive-green
Massachusetts tektite*

Martha’s Vineyard, Massachusetts

–

2.33

1.485

light olive-green

Comments: Tektites were first discovered in 1787 in Czechoslovakia (then Moravia) near the River Moldau, hence the name moldavite. It has been argued that tektites originated as a result of violent explosive activity on the Moon and were thrown all the way to the Earth’s surface. Other scientists, currently in the majority, argue that tektites are of terrestrial origin. The issue is being debated in a lively way.

Name: Moldavite is from the River Moldau; other tektite names are from the localities where  they occur.

by Joel E. Arem, Ph.D., FGA