BBC NEWS | Science & Environment | New minerals point to wetter Mars

BBC NEWS | Science & Environment | New minerals point to wetter Mars: "A Nasa space probe has discovered a new category of minerals spread across large regions of Mars.

The find suggests liquid water remained on Mars' surface a billion years later than scientists had previously thought.

The US Mars Reconnaissance Orbiter (MRO) spacecraft found evidence of hydrated silica, better known as opal.

The discovery adds to the growing body of evidence that water played a crucial role in shaping the Martian landscape and - possibly - in sustaining life."