Some quartz may not look like much on the outside but it might have cracks filled with crystals. This quartz is from a crack in a large rock on the coast of Maine. Sometimes it has small amounts of gold and silver with it, but mostly it is iron and sulfur. These are from a mine in Colorado that had a lot of silver. Selenite roses from near Canyoncito in central New Mexico.
Selenite crystals are a kind of gypsum.
Fluorite from a mine near White Sands, New Mexico. Fluorite is a source of fluorine and fluoride with is used to help prevent tooth decay. Azurite from a copper mine at Bisbee, Arizona. Azurite contains copper. Copper is used for pennies and for electrical wires.