There are some valuable minerals and ores that are largely overlooked by the recreational prospector. Dozens of these flouresce under ultraviolet light.
Scheelite is a very high grade ore of tungsten and fluoresces blue-white as seen below
Scheelite is found in many environments including granitic or intrusive rocks near margins or contacts, sedimentary rocks, replacement deposits and quartz veins. Scheelite is often associated with garnet, epidote, diopside, gold, topaz, molybdenite and fluorite. Scheelite has a specific gravity of 5.4 to 6.1, which is two to three times heavier than quartz. Scheelite may look like quartz but it will not scratch glass and is very brittle. Scheelite is white to light gray in color, ranges include: pale yellow, honey, snowy white to green when seen without an ultraviolet lamp.
Ore of uranium, autunite also fluoresces under ultraviolet light appearing yellow-green. Diamonds, uncut will mainly appear light blue. During those summer months, when it really is too hot to be out mining, you may consider investing in an ultraviolet light and getting out at night.