Have seenb conflicting info online as to what they use but looking at their own website they us ethe word "blend" which usually means its a mixture of mineral and vegetable wax, like many large scale candle makers.
Did you know that any amt of soy in a candle can be called a soy candle? No rules on how much is added to be called a soy candle. So fyi, only pure soy candles are pure soy.