Tektites and terrestrial glass like obsidian can be distinguished through several key characteristics. Tektites are formed from terrestrial debris ejected during meteorite impacts, while obsidian is volcanic glass formed from rapidly cooled lava. Here are some ways to differentiate them:
1. Chemical Composition: Tektites typically have a higher silica content and lack water, unlike obsidian, which contains more water and other volcanic elements. According to a study published in the Journal of Geophysical Research (Taylor, 1973), tektites have a unique chemical signature with low water content, often less than 0.02%.
2. Physical Appearance: Tektites often have a smooth, aerodynamic shape due to their formation process, whereas obsidian is usually more irregular and sharp-edged. Tektites may also exhibit a pitted surface, known as regmaglypts, similar to meteorites.
3. Refractive Index and Density: Tektites generally have a higher refractive index and lower density compared to obsidian. The American Mineralogist journal (Chapman, 1964) notes that tektites have a refractive index around 1.50, while obsidian's is typically higher.
4. Geographical Distribution: Tektites are found in specific strewn fields across the globe, such as the Australasian, North American, and Ivory Coast fields. Obsidian is more commonly found near volcanic regions.
5. Microscopic Examination: Under a microscope, tektites show a lack of crystalline structure, while obsidian may contain microlites or small crystals. The Earth and Planetary Science Letters (Koeberl, 1994) highlights that tektites are amorphous and lack the crystalline inclusions often found in obsidian.
By examining these factors, scientists can accurately identify tektites and distinguish them from terrestrial glass like obsidian.
