Microcrystalline/Cryptocrystalline minerals
			The specimen to the left is a microcrystalline, or massive form of quartz. The crystal form can only be seen under high power magnification.
Opal, Chert and Flint are all cryptocrystalline forms of silica. These three are commonly called fine grained silicates. Hand specimens are distinguished apart by their color: Opal being the lightest color, Chert the intermediate color, and Flint the darkest. All three exhibit the same mineral properties as quartz. Other common forms include Jasper, Chalcedony, Agate, Onyx, and petrified wood