I recently descovered a materal apparently called clinker. It's a deep purple color, a little reflective and has the apperance of ceramic, stone\brick and metal. It is irregular yet smooth and reminds me of expensive underused materals such as marble. It is however apparently free and considered always to be just a waste product.

Clinker is burned coal. what do you propose to do with it?

 

clink·er (klngkr)

n.

1. The incombustible residue, fused into an irregular lump, that remains after the combustion of coal.

2. A partially vitrified brick or a mass of bricks fused together.

3. An extremely hard burned brick.

4. Vitrified matter expelled by a volcano

I think it's also called 'slag' which is the waste byproduct of the smelting industries or foundries. It's the impurities that floats on top of the molten metal.... these are removed and cool down to give a vitreous solid like you've seen.

The klinkers are ground and used for abrasive blasting when rapid removal of material is desired and the finish is of little importance.

It is available in different grit sizes but is one of the most abrasive compounds used widely.

Just be aware that clincker can contain high amounts of toxic metals.