Detection of Silica-Rich Deposits on Mars

TLDR

Martian mineral deposits reveal past environmental conditions on the planet. Spirit found opaline silica deposits up to 91 % SiO₂ associated with volcanic material, present as soils and bedrock, formed hydrothermally and indicating past aqueous environments relevant to Mars habitability.

Abstract

Mineral deposits on the martian surface can elucidate ancient environmental conditions on the planet. Opaline silica deposits (as much as 91 weight percent SiO2) have been found in association with volcanic materials by the Mars rover Spirit. The deposits are present both as light-toned soils and as bedrock. We interpret these materials to have formed under hydrothermal conditions and therefore to be strong indicators of a former aqueous environment. This discovery is important for understanding the past habitability of Mars because hydrothermal environments on Earth support thriving microbial ecosystems.