February 25, 2015

Facts about our tektite moon rocks !

Real tektite moon rock

Some fact on moon rocks, item # RK010

Tektites, in the simplest terms are pieces of natural glass. Several natural glass types are found on the Earth. By outward appearance some tektites resemble obsidian the commonest of the natural glasses. Microscopically, tektites resemble glass more than obsidian in that they are almost completely devoid of any mineral crystals in their composition. The tektite glass is homogeneous in nature with the elements it contains dissolved and mixed. Tektites have much less water in their composition than obsidian's (often a thousand times less). Also obsidian's when heated will foam from the gases and water they contain and this is one method of tektite testing.. At the same temperature tektite glass may produce a few gentle bubbles. Tektites are made of a glass which melts at a far higher temperature and it is far more viscous.

Where did tektites come from? There have been several schools of thought over the last hundred years, but basically today it distills down to the Earth through the impact of a meteorite or comet. Tektites are fun to collect and websites that have tektites for sale can also be a good source of images.

In a cratering event, soil and rock are liquefied, or vaporized. There is question as to how long the tektites took to form and how high they were ejected. Was it a simple trajectory or did they travel high nearly into space? It is clear that part of the time they traveled at very high speed for they had to traverse great distances. The Australasian strewnfeild is thousands of kilometers across. It is thought by impact theorists that they are shaped in a plastic state as they spin. Later there may be some mostly minor shaping by ablation. In regard to the Australites, it is clear from

cross sectional analysis that they are a remelted object. Unlike the other tektites they received a major part of their final shape by ablation. However, the button portion of the posterior side has internal flow lines unchanged by remelting while those on the incoming ablated side are turned an pulled. Clearly, the internal structure was established and set, before the hypersonic ablation in the atmosphere.

Current chemical analysis of tektites indicates that there is a relationship to rocks only found on Earth. Fifteen rare earth elements have been used to show that their relative abundances are in exact relationship to their abundance in tektites. Including an anomaly in the amount of Europium. This depletion of Europium is connected to calcium and CO2 chemistry on the Earth. This depletion is exactly recorded in tektite glass. Melting a granite like rock will essentially make tektite glass composition. Oversimplification but actually close since many sedimentary rock thought to be used for tektites are derived from granites.

Tektites come in many sizes however, complete splash form types fall in the range of from one inch to four inches. Their weight in the 10 to 100 gram range. (Please excuse the generalizations, this is for the readers who have not seen them and have no idea of the exceptions that the tektite enthusiast will be familiar with.) They can be much smaller and much larger than the figures above, but for a simple average the range given may be useful.

Tektites are not usually smooth, they are usually pitted or grooved or a combination of both. More often than not they have a bald spot which is smooth. Many attempts have been made to explain the pitting. It has been thought to be from exposure to chemicals in the ground. Another explanation is that it is part of their form received before landing, perhaps during flight in the atmosphere. The inside of broken bubbles will often be shinny showing almost no etching, yet it has been exposed to the same chemicals for the entire time the tektite has been on earth. The back un-ablated side of as will often be textured and old looking while the ablated front surface and both surfaces of the flange will appear very fresh. Again the time spent in the ground was of course the same. The mechanism of texturing may be a process called spallation. Pieces of glass pop out of the surface coming through the atmosphere. Some experimentation has confirmed this as a possibility.

Tektites have been found with other artifacts in archaeological sites dating back thousands of years. They have a long history of use and significance to man. Ancient man in many places took advantage of the glassy nature of tektites and used them for making flaked tools. Later, they were considered to have religious significance in Asia, the colorful green varieties (Moldavites) of Europe have been used for jewelry for hundreds of years and are making a return as gems today.

Tektites are not found everywhere on the Earth. They are found in strewnfields; which are areas where the material has fallen upon the ground and the material is confined to the boundaries of the strewnfield. Tektites are found more or less randomly within the strewnfield. In the case of meteorite strewnfields the heavier fragments will be found at the farthest travel end of the dispersion ellipse.