This is a showdown of stories: both minerals bring tales from Earth’s depths to surface.

Omphacite tells the tale of high-pressure subduction, ocean floors crushed, altered, and uplifted back to the surface. This mineral takes in name “unripe grape” for its deep green colour.

Kyanite is an index mineral of specific formation conditions, its very existence marking a history of enormous pressures and unimaginable heat. The blue blades with directional hardness are often associated with mountain-building, the crystals whispering stories of lost mountain ranges eroded away so only the roots remain.

Read campaign highlights from the Round 1 matches won by Omphacite and Kyanite.

Happy Birthday, MimTimms! We love your enthusiasm, and how you’ve encouraged your friends, family, and students to discover (or rekindle!) their own love of rocks.

Voting for each match starts and ends at 06:00 GMT. Due to site limitations, the polls will continue to be visible until manually closed by volunteers, but only votes cast in the 24-hour period will be tallied.