Tektite,ablated, solid, splashform, anda, australite, philippinite, rizalite, bikolite, bicolite, indochinite, strewnfield, formation, sculpture, australasian, sale, bristol, impact, asteroid, meteor, meteorite, orientation, navals, grooves,
SOLID ABLATED (THEN SPALLED) TEKTITES
ABOVE: My collection of five complete flanged buttons (I keep them in a safe!). These ablated, but were small enough, so thermodynamically stable enough, to survive whole and not spall. Most larger specimens spalled with loss of their aerothermal shell.
I do not intend to go into any depth with Australites at this stage, but may expand this page in the future. They are amongst the most beautiful of tektites, forming at the distal end of the strewnfield. A number of websites and much literature has been dedicated to Australites. They are well understood and most people agree on how the different morphologies formed. An excellent website is located at www.australites.com.
ABOVE: A couple of Australite buttons in side profile, originally from the Futrell collection.
ABOVE: Half of an Australite button.
ABOVE: The anterior surface of a broken Australite button, originally from the Futrell collection.
By means of a brief summary, the original body (a sphere in this case) is interpreted to be solid or very close to solidification by re-entry stage. As the sphere re-enters it ablates and spalls. Spalling results in characteristic core shapes. Once ablation of material has crossed the equatorial margin of the specimen, a flange may begin to form. This leads to formation of ‘button’-type tektites. Further spalling may result in loss of the flange and creation of a lens. In larger specimens (>6g), which are less thermodynamically stable, the loss of the flange and creation of a core is inevitable. The flange may reform with further spalling resulting in conical core morphologies. If the button continues to ablate then end-members such as plates or bowls may form. As with other tektites there is a generalised, but not strict, formation route for the tektite. Ablation, spalling and flange formation combine to produce unique tektite forms.
ABOVE: An Australite core Anterior surface at bottom and anterior surface on the image to the left.
ABOVE: A nice, fresh core. Not that it is an indicator form as not all the frontal surface has flaked away.
ABOVE: Two different, typical cores. The specimen on the right is larger and comes from near Finke.
ABOVE: A typical set of water worn Australites from the dry lakes in Western Australia.
ABOVE: An idealised sequence of Australite Formation, note that cores can form at any stage. Cores can be large, whereas buttons are not found above 6g as the thermal instability of larger bodies favours spalling and core formation and as such, loss of any flange. Please click on image to enlarge (opens new window).
ABOVE: A clasification of the different Australite morphologies from Cleverly, 1986. Please click on the image to see a larger version (opens in a new window).
If you wish to find out more about Australites I highly recommend the following papers/books:
Baker, G. 1963d. Form and sculpture of tektites. In: Tektites (ed. O’Keefe, J. A.). Univ. Chicago Press, Chicago. pp. 1-24.
Cleverly, W. H. 1986. Australites from Hampton Hill Station, Western Australia. Journal of the Royal Society of Western Australia, Vol. 68, Part 4, p. 81-93.
McNamara, K. and Bevan, A. 1985 (2nd (revised) edition, 1991). Tektites. Western Australian Museum. pp. 28. (Currently in print!)
Further references can be found in my extensive bibliography, many of which can be downloaded for free..