White flour which has been stored with truffles or infused with truffle oil. It is expensive, but nowhere near the unreal lavishness of actual truffles.

Truffle flour has the physical properties of flour, but is redolent with truffle smell (or what we blighters must assumeis truffle smell, since even getting a whiff of the actual fungus is quite difficult). It's a bit like flower scent, but not as cloying. A heavy, enveloping smell, it reminds me of dark purple velvet.

This set off a bout of daydreaming about truffles as cognitive enhancers, which would account for their great price and traditional value. But I'm pretty sure that had more to do with my thinking about the chakras and having read Dune recently than it did with any brief inklings of enlightenment.