TEKTITE: Moldavite, Czechoslovakia (6.4)
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 Value
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Tektite Information
| Data | Value |
| Name | Tektite |
| Varieties | Australite, Bikolite, Billitonite, Darwin Glass, Moldavite |
| Crystallography | Amorphous-a glass. |
| Colors | Black, green, greenish brown, brown in moldavites; other tektites black, colorless to brown; usually opaque. |
| Luster | Vitreous. |
| Hardness | 5.5-6.5. |
| Density | 2.21-2.96 [see table). |
| Cleavage | None. Fracture corichoidal. Brittle. |
| 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. |
| Spectral | Not diagnostic: Moldavites may show two vague bands in the blue and orange. |
| Formula | Silica (75%) + Al, Fe, Ca, Na, K, Mg, Ti, Mn. |
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 |
Density |
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.
