Agate Vs. Onyx

Agate is a very popular gemstone composed of silicon dioxide.^[1] Onyx is also a very popular gemstone and its chemical composition is also silicon dioxide.^[2]

Quick Facts on Differences of Agate and Onyx

For a quick recap of the differences agate and onyx:

• While both agate and onyx can be opaque or translucent, agate can be transparent.
• While both agate and onyx can be vitreous or waxy, in terms of luster, agate can be greasy.
• Agate can be commonly red or white while onyx can be commonly black.
• Agate's specific gravity is lower than onyx - agate ranges from 2.6 to 2.64 and onyx is 2.651.

Quick Facts on Similarities of Agate and Onyx

The similarities of agate and onyx include:

• In terms of crystallography, agate and onyx both can be hexagonal or trigonal.
• For chemical formulas, agate and onyx both are SiO2.
• Agate and onyx both streak white.
• Agate's rarity is similar to onyx.
• Agate's hardness overlaps with onyx - agate ranges from 6.5 to 7 and onyx is 7 on the Moh's scale.

Summary of Agate

Agate is a mineral that belongs to the quartz family. It is typically found in volcanic rocks and is characterized by its banded appearance, which is caused by the deposition of different minerals in layers. The mineral is identified by its hardness, which ranges from 6.5 to 7 on the Mohs scale, and its translucent to opaque appearance. While agate is typically associated with shades of brown and gray, it can also be found in a variety of colors, including blue, green, pink, purple, and red.

Summary of Onyx

Onyx is a mineral that belongs to the chalcedony family, which is a type of quartz that is formed by the deposition of silica in the cavities of rocks. It is a cryptocrystalline mineral, which means that its crystals are too small to be seen with the naked eye. Onyx is typically black, but it can also be found in other colors such as white, gray, brown, and green. It has a waxy luster and a smooth, polished surface.

Table Comparison of Agate vs Onyx