Agate                         Mineral Group: SILICATES

  • Agate is a form of chalcedony which is a variety of quartz.
  • The most common use for agate is as an ornamental stone. It is used for jewellery, vases, book ends, sculptures, table tops, and tiles. It is also collected by rockhounds because of its natural beauty.
  • Agate is composed primarily of microscopically crystallized silica (SiO2) and often occurs as a cavity filling in lavas.

Chachahuen Agate, Sierra de Chachahuen
Newquen, Patagonia, Argentina
  • This slice of white, gray & brown banded agate has been cut with a diamond blade and polished to a shiny, glassy finish. If tapped, it sounds like glass. It is translucent. The bands are concentric, taking the shape of the agate nodule or geode it filled in.

  • This agate nodule has been cut in half and polished. Notice how the inside is solid but looks translucent and milky.


  • Natural colors are brown, black, tan and white. Since agate slices come from geodes and nodules, the shape of the slice reflects the most common geode shapes. The most common shapes are round and oval.


Crazy Lace Agate
  • Crazy Lace Agate is a descriptive name that refers to the banding that undulates and swirls
  • the primary colours of the banding are brown, cream, red and orange alternating in thin lines
  • the source of most Crazy Lace agate is Mexico
  • it is a favourite stone used in lapidary to make cabs (cabochons) for pendants & earrings
  • stones are opaque to tranlucent
  • it has a hardness of 6.5 to 7 on the Moh's scale of hardness and takes an excellent polish
Lake Superior Agate
  • Agate can be found either as rounded nodules or as seam agate

Seam Agate slice Mamainse Point, Lake Superior
(between Sault Ste. Marie & Wawa) Ontario  CANADA
 Blue Lace Agate
  • Blue Lace Agate is known by its distinctive pale blue and white banding
  • its delicate decorative banding resembles lace
  • the source of Blue Lace Agate is in Africa - South Africa & Namibia
  • it has a hardness of 6.5 to 7 on the Moh's scale of hardness and takes an excellent polish

Coloured Agate Slices
  • This slice of agate has been dyed to show how a natural stone can have its color changed.
  • Many agate slices are available in gift shops with bright pink, purple & green colors. They have all been dyed because people like the colors. The colors are not natural. They are artificial. The agate slices are soaked in "mineral baths" and heated to give them the brilliant artificial colors.
  • Agate is formed in layers and usually follows the shape of the cavity.


SPECIMEN LOCATION: Royal Ontario Museum, Ontario, CANADA

Below are some decorations that have been made from agate slices.
Some of the projects below are from "The Agate Art Book 1" by N. Gere, E. Berndl and B. Kovacs, presenters at an agate art workshop.



Agate Art uses agate slices and traditional stained glass techniques to create works of art that are unique because no agate slice is alike.


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