Agate Vs. Opal

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

Quick Facts on Differences of Agate and Opal

For a quick recap of the differences agate and opal:

• While both agate and opal can be translucent or transparent, agate can be opaque.
• For chemical formulas, agate is SiO2 while opal is SiO2· nH2O.
• While both agate and opal can be vitreous or waxy, in terms of luster, agate can be greasy and opal can be pearly.
• While both agate and opal can be commonly red, agate is often white.
• Agate's specific gravity is higher than opal - agate ranges from 2.6 to 2.64 and opal ranges from 1.98 to 2.25.

Quick Facts on Similarities of Agate and Opal

The similarities of agate and opal include:

• Agate and opal both streak white.
• Agate's rarity is similar to opal.

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 Opal

Opal is a mineraloid that is formed from the silica-rich water that permeates through the earth's crust. It is a beautiful gemstone that is known for its unique play of colors. Opal is a non-crystalline mineral that is made up of tiny spheres of silica, which diffract light in a way that creates a rainbow of colors. The colors of opal can range from white, gray, and black to red, orange, yellow, green, blue, and purple.

Table Comparison of Agate vs Opal