Tektite (likely Australite)

Hardness: 5-6.5 on Mohs scale (can vary); Color: Typically black, dark brown, or dark gray; Luster: Resinous to waxy, sometimes dull; Crystal Structure: Amorphous (mineraloid, not a true crystal); Cleavage: None, conchoidal fracture (glass-like); Specific Gravity: 1.05-1.10. It is lightweight for its size.

Formed from terrestrial rock melted by a hypervelocity meteorite impact, ejected into the atmosphere, and solidified upon re-entry. The geological age varies depending on the specific impact event, but most known tektite strewn fields range from millions of years ago to relatively recent (e.g., the Australasian strewn field is ~0.8 million years old). The heating and cooling process is extremely rapid.

Primarily of scientific interest for studying impact events and extraterrestrial processes. Also highly valued by collectors due to their unique formation and extraterrestrial association (though they are Earth material). Some are cut and polished for jewelry, but this is less common than for other gemstones.

Tektites are natural glass objects formed from terrestrial debris ejected during large meteorite impacts. They are not meteorites themselves, but rather Earth material that was melted and flung into the atmosphere, solidifying into glass as they fell back down. Australites are a specific type of tektite found in Australia, known for their button-like or other aerodynamic shapes caused by high-speed atmospheric re-entry. The streaky patterns on the surface of some tektites, as seen in the image, are a result of this rapid cooling and flow during formation.

In the field, tektites are identified by their characteristic dark, glassy appearance, often with aerodynamic shapes (especially Australites). They are typically found in strewn fields, which are specific geographic areas where they landed after an impact. Key features to look for include: glass-like texture, lack of vesicles (unlike volcanic glass/obsidian), often displaying flow lines, grooves, or button/flange shapes (like the one possibly indicated by the surface texture in the image). The specimen's dark color, glassy luster, and the apparent flow lines or pitted surface suggest it is indeed a tektite. Common locations for Australasian tektites are Australia, Southeast Asia, and parts of China. For collectors, the presence of specific shapes (e.g., buttons, dumbbells, teardrops) and surface textures (e.g., pitting, grooving, flow lines) are important identifying characteristics.