Thermal borehole

A Thermal Borehole penetrates to Planet's mantle and provides significant mineral and energy bonuses. Borehole squares provide +6 minerals and +6 energy, but produce no nutrients and cannot be farmed. Thermal Boreholes cannot be built adjacent to other boreholes, nor on slopes (land squares adjacent to other land squares of lower altitude). Thermal Boreholes have a significant negative ecological impact.