Agate, is a distinctly banded variety of Chalcedony, is a variety of Quartz gemstones composed of layers of quartz, sometimes of different colors. When it is concentrically banded (often in rather wild patterns) it is called by the subvaritey name "agate." When it is in flat layers/bands it is called by the subvariety name "onyx." Agate usually occurs as rounded nodules or veins in rock such as volcanic lava. The layers of quartz are often concentric. The composition of agate varies greatly, but silica is always predominant, usually with alumina and oxide of iron. Agate comes in most colors.

The cryptocrystalline varieties of quartz may be separated into two types; fibrous and microgranular. Chalcedony is the general term applied to the fibrous cryptocrystalline varieties. Agate is an example of a fibrous cryptocystalline banded chalcedony variety of quartz. Carnelian, Chrysoprase and bloodstone are other chalcedony varieties. Chert is the general term applied to the granular cryptocrystalline varieties of quartz, of which flint and Jasper are examples.

It is a mineral generally of secondary origin, forming in cavities and veins by deposition from meteoric groundwater containing gelatinous silica from the weathering of silicate minerals. It can also form by deposition from late hydrothermal solutions at or near the earth's surface under conditions of low temperature and low pressure. Agate is commonly associated with siliceous volcanics, occurring as vein or vesicle filling. It occurs as a petrifying agent in fossil wood and bone. Agate is frequently found lining or filling rock cavities and fissures, sometimes forming geodes.

Category: Quartz variety
Chemical formula: Silica, (SiO2 - Silicon Dioxide)
Colors: Clear, Brown, Green, Orange, Purple, Rose, Black, Yellow, etc.
Chemical Formula: SiO2
Hardness: 7.00
Density: 2.61
Refractive Index: 1.53 - 1.54

Care of Gemstone
Use mild soap and warm water is the easiest and safest cleaning solution. Use soft cloth to dry.
Avoid bumping on hard surfaces as gemstones are delicate.
Do not expose gemstone to sunlight for a long time. Keep it in an area of humidity to protect it from over-drying.
It is most desirable to store gemstone in a fabric-lined case or in a box with dividers or separate compartments to avoid the gemstone surface being scratched by other hard objects.