Definition
Tenham is a meteorite classified as an H5 ordinary chondrite that fell in Queensland, Australia, on 14 December 1885. It is noted for its well‑preserved shock‑metamorphic features and has been extensively studied in planetary science.
Overview
The Tenham meteorite was observed falling near the rural locality of Tenham, approximately 30 km east of Charleville in the state of Queensland. Contemporary reports describe a bright fireball followed by a loud report and the impact of several stones on the ground. Subsequent recovery efforts yielded a total recovered mass of roughly 100 kg, consisting of multiple fragments. The fall is one of the historically significant meteorite events in Australia and provides a classic example of a high‑shock, ordinary chondrite.
Etymology/Origin
The name “Tenham” derives from the name of the pastoral station and surrounding area where the stones were found. As is customary in meteoritics, the meteorite is named after the nearest geographical place to the fall site.
Characteristics
- Classification – Ordinary chondrite, group H (high iron), petrologic type 5, indicating extensive thermal metamorphism that resulted in the homogenisation of chondritic minerals.
- Shock Stage – Assigned shock stage S5 (or higher in some studies), reflecting intense shock pressures (≈30–45 GPa) experienced during the impact event.
- Mineralogy – Dominated by olivine (Fa₁₈–₂₀), low‑calcium pyroxene (En₈₀–₈₅), metallic Fe–Ni alloy, and sulfides (troilite). High‑pressure polymorphs such as maskelynite (shocked plagioclase) and ringwoodite have been identified in thin sections.
- Physical Properties – Bulk density about 3.5 g cm⁻³; magnetic susceptibility typical of H‑group chondrites.
- Scientific Importance – Tenham’s high shock level makes it a reference specimen for studying impact‑induced phase transformations, shock melt veins, and the formation of high‑pressure minerals. Analyses of Tenham have contributed to understanding the pressure–temperature regimes of planetary collisions and the mechanical behaviour of silicate materials under shock.
Related Topics
- Ordinary Chondrites – The most common class of stony meteorites, subdivided into H, L, and LL groups based on iron content.
- Shock Metamorphism – The suite of structural and mineralogical changes in rocks caused by high‑pressure shock waves, exemplified by Tenham’s maskelynite and high‑pressure polymorphs.
- Meteorite Falls in Australia – Other notable Australian falls include the Murchison (1908), Mundrabilla (1912), and the 2021 Pictou fall.
- Planetary Impact Processes – Studies of terrestrial meteorite impacts inform models of crater formation and planetary crust evolution.