Minna often uses different kinds of agates in her jewelry and even in book decoration. For example, Cascading Waters in the Necklaces page is blue gate.
Agate (pronounced /ˈæɡət/) is a microcrystalline variety of quartz (silica), chiefly chalcedony, characterised by its fineness of grain and brightness of color. Although agates may be found in various kinds of rock, they are classically associated with volcanic rocks and can be common in certain metamorphic rocks. Inside, agate reveals an amazing variety of colors and patterns and a distinct banding that distinguishes it from other types of chalcedony.
Other forms of agate include Lake Superior agate, carnelian agate (usually exhibiting reddish hues), Botswana agate, Ellensburg blue agate, blue lace agate, plume agates, tube agate (with visible flow channels), fortification agate (which exhibit little or no layered structure), fire agate (which seems to glow internally like an opal) and Mexican crazy-lace agate (which exhibits an often brightly colored, complex banded pattern) also called Rodeo Agate and Rosetta Stone depending on who owned the mine at the time.