Meteorite impacts have long been debated as a cause of mass extinction on Earth. When they hit, meteorite impacts load the atmosphere with dust and cover the Earth’s surface with debris. This is thought to trigger ‘Impact Winter’, whereby sunlight is blocked from reaching the earth’s surface leading to catastrophic ecosystem collapse. The bigger the hit, the more severe the effects. But does it really work like that? In this talk I’ll show you that there is actually no correlation between size of impact and extinction intensity over 600 Myrs of multicellular life. Instead, it is the mineralogy of the target rocks that dictates extinction intensity, in particular their K-feldspar content. Weird. To find out how this benign mineral triggers mass extinctions, you’ll have to come along to the seminar!