"Alternatively, ‘Skull Hill’ could be an igneous rock eroded from a nearby outcrop or ejected from an impact crater," Deahn continues. "On Earth and Mars, iron and magnesium are some of the ...

UNIFORM with the “Rock Minerals” of the same author, now in its second edition, the work which Prof. Iddings has now completed will take an assured place as the fullest and most comprehensive ...

Quantitative Classification of Igneous Rocks Based on Chemical and Mineral Characters, with a Systematic Nomenclature. By Whitman Cross Joseph P. Iddings Louis V. Pirsson Henry S. Washington ...

NASA says Skull Hill’s dark color is reminiscent of meteorites found in Gale crater by the Curiosity rover, but analysis of its chemical composition may identify it as igneous rock eroded from a ...

Forbes contributors publish independent expert analyses and insights. Amanda Kooser covers the quirky side of science and space.

Instead, it may be an igneous rock formed from magma or lava, containing iron and magnesium-rich minerals such as olivine or pyroxene. These minerals are common in volcanic rocks on both Earth and ...