Ritual Sites Sell Lots Of These Black Candles For High Prices.

Here is what they say they are good for:

Burning black with any other color dissolves negative energies! Get Protection, Use For Hex-Breaking, Repel Black Magic, Reversing All Kinds of Banishing Rituals, Destroying Evil or Negativity, Repelling. Healing Powerful Illnesses and Pain, Opens up the deep Levels of Consciousness.
Used to Banish Bad Habits. Use with Caution.

..........and you thought they were just good for using on Angel Chimes.