I found a cool formula:

How to make radio minerals.

Synthetic crystals are composed of lead and sulphur. The lead is first melted, then sulphur is added, the mixture being stirred with a carbon rod until it forms into a black solid mass. After being cooled it is finely powdered, and about 10% of its own weight of powdered sulphur is added. The whole preparation is then fused.

The MOST SENSITIVE mineral was galena (Lead Sulphide- PbS), which was very sensitive also to mechanical vibration, and easily knocked off the sensitive point; the most stable were perikon mineral pairs; and midway between was the pyrites detector, which is approximately as sensitive as a modern 1N34A diode detector.[16][17]

Since Moray started out by building self powered crystal sets that could operate speakers from a natural occurring found mineral but later started building a SYNTHETIC crystal reputedly with some radioactive element added(that created enough power to light a 10kw bank of light bulbs)- that, if the above formula was used with the inclusion of some radioactive material, it could produce a crystal that produces power.