File:S73-15083.jpg

English: S73-15083 (4 Jan. 1973) --- A photomicrograph of spheres and fragments in the "orange" soil which was brought back from the Taurus-Littrow landing site by the Apollo 17 crewmen. Scientist-astronaut Harrison H. "Jack" Schmitt discovered the "orange" soil at Shorty Crater during the second Apollo 17 lunar surface extravehicular activity (EVA). This lunar material is being studied and analyzed by scientists in the Lunar Receiving Laboratory at the Manned Spacecraft Center. It has been discovered that the orange color was caused by the very fine spheres and fragments of orange glass in the midst of darker colored, larger grain material. Chemical analysis of the "orange" soil sample has shown the material to be similar to some of the samples brought back from Apollo 11 (Sea of Tranquility) site several hundred miles to the southwest. Like those samples, it is rich in titanium (8%) and iron oxide (22%). But unlike the Apollo 11 samples the "orange" soil is unexplainably rich in zinc--an anomaly that has scientists in a quandary. Some of the early expectations, based on the color of the sample reported from the moon, have not been borne out by the initial tests: the sample is not high in volatile elements, nor do the minerals contain substantial amounts of water. These would have provided strong evidence of volcanic activity. On the other hand, the lack of agglutinates (rocks made up of a variety of minerals cemented together) indicates that the orange glass is probably not the product of meteorite impact-strengthening the argument that the glass was reproduced by volcanic activity. The sample in this picture, magnified 31.5 times, shows particles in the 150-250 micron size range (fine sand). Finer particles, similar in size to particles making up silt, are more distinctly orange in color.