black agate vs

Black agate and onyx are two distinct gemstones, both belonging to the chalcedony family. While they share similar visual characteristics, there are differences in their composition, sources, and sometimes in their use within the jewelry industry.

Black Agate:

Origins and Geology:

  • Origins: Black agate is a variety of chalcedony, which is itself a form of microcrystalline quartz. It is found in various locations globally, including Brazil, India, Australia, Mexico, and the United States.

Physical Properties:

  • Color: Black agate, as the name suggests, is typically black or very dark brown. It often displays banding patterns or other distinctive markings.
  • Transparency: It is usually translucent to opaque.
  • Luster: Black agate can have a waxy to dull luster.
  • Mohs Scale: Agate, in general, has a hardness of 6.5 to 7 on the Mohs scale.


  • Jewelry: Black agate is commonly used in jewelry, such as beads, cabochons, and cameos.
  • Decorative Items: It is also used in ornamental items like carvings, beads, and small sculptures.

Metaphysical Properties:

  • Protection: Black agate is often associated with protection and grounding.
  • Balance: It is believed to bring balance and emotional stability.


Origins and Geology:

  • Origins: Onyx is also a type of chalcedony, and it forms in the gas cavities of lava. Major sources include Brazil, India, Uruguay, and the United States.

Physical Properties:

  • Color: Onyx is typically black, but it can also have bands of white, brown, red, or other colors. Sardonyx is a specific type of onyx with brown and white bands.
  • Transparency: Onyx is generally translucent to opaque.
  • Luster: It has a waxy to vitreous luster.
  • Mohs Scale: Onyx has a hardness of 6.5 to 7 on the Mohs scale.


  • Jewelry: Onyx is widely used in jewelry, especially for beads, cabochons, and cameos.
  • Carvings: It is used for carving small decorative items and cameos.
  • Decorative Items: Onyx is also used in ornamental items, such as vases and bowls.

Metaphysical Properties:

  • Protection: Onyx is associated with protection and strength.
  • Grounding: It is believed to provide grounding and stability.

Black Agate vs. Onyx: Key Differences


  • Black Agate: Typically solid black or very dark brown, often with banding patterns.
  • Onyx: Black with bands of white, brown, red, or other colors. Sardonyx is a variety with brown and white bands.


  • Black Agate: Waxy to dull.
  • Onyx: Waxy to vitreous.


  • Black Agate: Translucent to opaque.
  • Onyx: Translucent to opaque.


  • Black Agate: Used in jewelry and decorative items.
  • Onyx: Widely used in jewelry, carvings, and decorative items.

Metaphysical Associations:

  • Black Agate: Associated with protection and balance.
  • Onyx: Associated with protection, strength, and grounding.


While both black agate and onyx share similarities, such as their color and use in jewelry, there are distinctions, especially in terms of banding patterns. Black agate often displays more prominent and varied banding, while onyx is characterized by its solid black color or distinctive bands of contrasting colors. The choice between black agate and onyx may depend on personal preferences, the desired aesthetic, and the intended use of the gemstone, whether in jewelry or decorative items. Both gemstones have unique qualities and can add a touch of sophistication to various creations.


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