Found on bark on firewood. Possibly oak. Initially I thought it was paint. It was so bright and vivid after a rain. Ammonia caused to lighten to a yellowish. A few small pieces of wood with fungus put in a few tablespoons of ammonia turned the liquid very yellow pretty quickly. The color is accurate. The brightest photos were taken just after a rain. Originally found 6/2/17. All but one photo taken on observation date.