This is a very fine powder of aluminum. It can be used to make thermite (a mixture of iron oxide (rust) and aluminum), which burns very hotly and is used both for welding and for destroying things. It doesn't explode, it just create an extremely intense heat and the product of the reaction is white-hot molten iron.
A friend related the story of being in the signal corps of the army: Every piece of communications equipment that involved cryptographic components came as standard issue with a thermite blanket. In case if imminent enemy capture, the soldiers were instructed to put the thermite blanket over the machine and light it. The burning blanket would then reduce the machine to a puddle of molten slag. In dull moments they entertained themselves by having the blankets melt through the engine blocks of broken down jeeps.
Please note that finely powdered aluminum like this can be explosive under the right conditions. There was a disaster in my town in the summer of 2003, reported by the local newspaper as being an aluminum dust explosion: Here are three articles about it: 1, 2, 3.
Source: United Nuclear
Contributor: United Nuclear
Acquired: 11 April, 2003
Text Updated: 27 October, 2007
Price: $12/8 ounces
Sample Group: Powders