Sounds very interesting. Lightning sometimes creates large radiating Lichtenberg figure patterns in grass and in as glassy fulgurites in sandy soil. Also, lightning sometimes creates melted Lichtenberg figure patterns on the surface of concrete. These are true Lichtenberg figures.
Natural mineral formation and crystallization sometimes create branching (dendritic) patterns that look similar to Lichtenberg figures. However, these dendrites are deposited in a completely different manner than true Lichtenberg figures that do not involve any high voltage. For example, plume agate and manganese oxide sometimes form patterns which look quite similar to Lichtenberg figures:
I'm very interested in what you have found. Do you have any pictures of your specimens and can you provide any information about where the minerals or crystals were found?
I can also be reached at 630-964-2699 if you'd like to discuss further.