Agate
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Agate is a fine-grained variety of quartz. It forms in layers of silica in the cavities of rocks. It is very hard, a 7 on the mohs scale. There are many varieties of agate, some of them very colorful. The different varieties get their names from the colors and patterns in the rock. The names of some of the agates actually describe their appearance, such as banded agate, moss agate, crazy lace agate and leopard skin agate.
What Is Agate?
Agate is the name given to a group of silicate minerals that are made up primarily of chalcedony. Chalcedony is a member of the quartz family of minerals. Like quartz chalcedony is silicon dioxide with a chemical formula of SiO2. The main difference between quartz and chalcedony is in the size of the individuals crystals. Chalcedony is termed microcrystaline meaning that individual crystals are too small to be seen by the naked eye.
How Is Agate Formed?
Agate is formed by mineral rich groundwater seeping into cavities of existing rock. As the water passes through a little bit of the mineral, silicon dioxide is left behind. In a process that can take many thousands of years, layer upon layer of minerals build up on the walls of the cavity.
How Does Agate Get Its Colors?
Agate can be very colorful with colors ranging from white, gray and black to almost every color of the rainbow. The colors come from impurities in silica rich ground water. These impurities are actually other minerals like iron oxide, magnesium, and chromium. Banded agates are formed by changes in the chemical composition of the groundwater over time, creating a record of environmental changes.
How Much Is Agate Worth?
Agate has been valued as a simiprecious stone for thousands of years. What agate is worth depends on individual beauty and how easy it is to find. Agate as a whole is pretty common. It is a very hard material that resists the weathering that eventually breaks down all rocks. It is commonly found in stream beds. The value of agate increases with rich colors and interesting patterns. Crazy lace agate, picture agate, and landscape agate are examples of interesting patterns. Mulitiple colors and intense colors also increase the value of agate. Agate with desirable qualities has more value when it is hard to find. Some agates are only found in one location. Fire agate and fairburn agate are two pricy agates because of their scarcity.
Mineral Properties of Agate
Chemical formula: Silicon dioxide SiO2
Color(s): many colors and patterns
Streak: white
Luster: vitreous, glassy
Transparency: transparent to translucent
Crystal system: triagonal
Specific Gravity: 2.6
Hardness (Mohs): 7
Cleavage: none
Fracture: conchoidal
Uses: jewelry, bookends, wind chimes, and other decorative items.
Location: widespread occurance
Metaphysical Properties of Agate
Agate has a balancing, centering influence on the the mind and body, while improving mental ability and concentration. It can help reverse negative energy. Agate is soothing and calming.
