File:S73-15171.jpg

English: S73-15171 (4 Jan. 1973) --- These orange glass spheres and fragments are the finest particles ever brought back from the moon. Ranging in size from 20 to 45 microns (about 1/1000 of an inch) the particles are magnified 160 times in this photomicrograph made in the Lunar Receiving Laboratory at the Manned Spacecraft Center. The orange soil 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 extravehicular activity (EVA). This lunar material is being studied and analyzed by scientists in the LRL. The orange particles in this photomicrograph, which are intermixed with black and black-speckled grains, are about the same size as the particles that compose silt on Earth. Chemical analysis of the orange soil material has shown the sample to be similar to some of the samples brought back from the 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. This Apollo 17 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 produced by volcanic activity.