Carbide

An inorganic compound of calcium and carbon, with the chemical formula CaC2. The substance occurs as a white-yellow to gray-blue crystalline powder or lumps. Formally, calcium carbide calcium salt of ethyne.
In a milk churn with lid gives a loud bang and if your are lucky you can catch a huge flame.
Every last day of the year celebrates the carbide club with an annual geocaching event in Landgraaf.