A total of 164 microspheres were found insitu in a Lower Triassic sandstone that lies unconformably on Permian sediments. The sandstone has an age of approximately 250 million years. The primary constituent of the microspheres is native lead (96%). Isotope studies indicate an age of 1 billion years for the lead. The origin of these microspheres is unknown but an extraterrestrial source best fit the available data.

A total of 152 sandstone samples were collected from an area which covered over 5,000 sq. mi. (12,500 sq. km.) An which had a stratigraphic thickness of over 900 feet (275 meters). Forty-eight (48) of the most friable samples were disaggregated by hand using a 4-inch rubber stopper on a hard rubber pad until 100 ml., of disaggregated sandstone was collected. The samples were screened on a set of 27 screens ranging in size from 44 microns to 4 mm. Quartz and other low specific-gravity minerals were floated off using a heavy liquid. The heavy minerals were weighted and identified. The above method differs from a normal heavy mineral study only in that all the heavy minerals from both fine and coarse screens were identified. Of the 48 disaggregated samples, 15 were found to contain 164 microspheres. These were always found on the +0.35 mm. Screen sizes.

The microspheres were discovered by accident only because the heavy minerals of the larger screen sizes were examined.

The microspheres are non-magnetic and many have a pitted surface; they are round to slightly elliptical and are easily seen by the unaided eye. Many contain 'tails' some of which are corkscrew shaped. Spectrographic analysis show the impurities to be SiO₂ (1-2%), FeO₂ (1%), Al₂O₃ (0.2%), CaO (0.1-0.2%), MgO (0.1-0.2%), B₂O₃ (0.1%), TiO₂ (0.05%), MnO (0.001-0.01%), CuO (0.003%), and NiO (0.001%).

The above mentioned heavy mineral study is but a small portion of a much more comprehensive study of the Triassic Hawkesbury Sandstone located in the Sydney Basin of eastern Australia. The study, "Stratigraphy, Structure and Petrology of the Hawkesbury Sandstone" was never published and was part requirement for a PhD at the Department of Geology and Geophysics, University of Sydney, Australia.