Unlike other gemstones, each Agate gemstone is unique to itself – even when cut from within the same area. It’s distinguishing elements comprise banding or swirls of different colors or multi-colored translucency
Belonging to a variegated form of the Chalcedony family, the Agate is derived from a silicon dioxide in the form of microscopic quartz crystals. An Agate can be defined as a banded chalcedony that has formed into different patterns and colors due to the influence of various minerals and other factors.
Formation of these gemstones have occurred over millions of years as a build up of microcrystals formed within empty pockets inside host rocks – and commonly volcanic rocks.
Agates can be any color from blues whites and grays through to yellows, oranges and reds and are determined by the types of minerals found within them. .
Lake Superior Agates tend to be yellow, orange and red in color, due to the influence of iron in them and have concentric circles of color that resemble the cross section of a tree. Many Agates can be found at Lake Superior– with Minnesota calling itself the “Agate Capital of the World.
Agate is a porous stone that can be easily dyed so that its original color can be enhanced.
Names of agates have been attributed to the stones based primarily on their appearance. For this reason there are a wide range of “varieties”. Some of the names you may come across include:
Eye Agates: Beads of crystals have formed with the silica dioxide cavity to create a pattern resembling little eyes.
Fortification Agates: These have concentric circles are termed Fortification Agates as found with the Lake Superior agates. – The name Fortification was derived because their layers look like fortress walls.
Geode Agates: A variety of silica mineral crystals with a centre hollow, due to incomplete formation of silica rich water in the rocks during formation of the gemstone.
Lace Agates: Has pretty blue and white swirls that look like clouds in the sky
Moss Agates: These have patterns that resemble plants and trees. The agates are mainly made up of iron or manganese oxide.
Plume Agates: Resemble ferns or feather due to strands of mineral inclusions
Seam Agates: The patterns have occurred due to the silica mineral crystals forming within cracks and not rounder pockets
Shadow Agates: Optical illusions creating a shadowy effect occur when it is rocked backwards and forwards and light reflects off the translucent bands.
Tube Agates: Tube like patterns have occurred due to thin mineral rods forming prior to the chalcedony crystal formation.
Water Line Agates: Stacks of parallel lines of color that were created uniformly