Boronite was a standard explosive, roughly nine times more powerful than dynamite, used by Earth's far-flung human colonies. Boronite contained ammonium nitrate and reduced nitroglycerin to make its explosions less dangerous.
The early settlement of Trenzalore used boronite to explode bedrock in order to reach underground hot springs. The leftover boronite was shelved and later on Tiberius Gluck took some for his personal use in the Outland. The Eleventh Doctor defeated the Autons that tried to kill him with a tube of boronite by setting the boronite off on board the Lifeboat, causing them to sink to the bottom of Lake Lagda. (PROSE: Strangers in the Outland)