the nickel content was always close to 0.3 wt%, a group of five standard oxides (MgO, Na2O, P2O5, SO3, and Cl) each had content above trace-level with a combined group content of 6.8 +/- 2.4 wt%, the SiO2 levels ranged between 8 wt% and 0 wt%, and the other eight APXS standard oxides had either 0 wt% content or only trace level content. Size of Blueberries The Opportunity science team published three papers that studied variations in hematite spherule size. They found spherule size variation by location and elevation. In the earliest paper, a team of Opportunity rover scientists reported on studies of all the soil materials found between the landing site in Eagle Crater to the location on sol 552 of the rover's traverse (between Endurance Crater and Victoria Crater). They found that in a sample of 696 blueberries, disregarding any non-spherical blueberries from the sample, the blueberries' average major axis to be about 2.87 mm (just over one-tenth inch). They also discovered that blueberries found within soils are typically smaller than blueberries found in the outcrops. They noted the size of the blueberries tends to decrease with decreasing latitude. The Opportunity team found many fragmented blueberries and suggested the fracturing occurred after spherule formation. They believe the fracturing either be from meteoric impacts or the "same process" that "fractured the outcrop". However, the team notes this would not explain the presence of the smallest hematite spherules detected. The smallest are close to perfectly spherical and therefore cannot be explained by fracturing or erosion. The Opportunity team also found that blueberries uncovered by the Rock Abrasion Tool aboard Opportunity were 4.2 +/- 0.9 mm (0.16 inches) major axis length at Eagle Crater and 4.5 +/- 0.6 mm at Endurance crater, about 2.2 +/- 0.5 mm (0.087 inches) at Vostok and about 3.0 +/- 0.2 mm (0.12 inches) at Naturaliste (crater). Those found in "the plains" south of Endurance Crater were smaller (1-2mm or 0.04-0.08 inches) than those of Eagle and Endurance craters. The second paper studying spherule size extended the study area 2-3 km further south on the plains to Victoria Crater. This paper reported similar observations to the first but went further to suggest the observed size variation might be due to sampling different sediment stratigraphic levels at different locations. Additionally, it suggested simple variations in diagenetic conditions were linked to changes in spherule size. The third paper