AllMineralsRock
Agate Vs. Chalcedony
Agate is a very popular gemstone composed of silicon dioxide.[1] Chalcedony is also a very popular gemstone and its chemical composition is also silicon dioxide.[2]
Quick Facts on Differences of Agate and Chalcedony
For a quick recap of the differences agate and chalcedony:- While both agate and chalcedony can be vitreous or waxy, in terms of luster, agate can be greasy and chalcedony can be dull.
- While both agate and chalcedony can be commonly red, agate is often white.
Quick Facts on Similarities of Agate and Chalcedony
The similarities of agate and chalcedony include:- Agate and chalcedony both can be opaque, translucent or transparent.
- In terms of crystallography, agate and chalcedony both can be hexagonal or trigonal.
- For chemical formulas, agate and chalcedony both are SiO2.
- Agate and chalcedony both streak white.
- Agate's rarity is similar to chalcedony.
- Agate's hardness overlaps with chalcedony - agate ranges from 6.5 to 7 and chalcedony is 7 on the Moh's scale.
- Agate's specific gravity overlaps with chalcedony - agate ranges from 2.6 to 2.64 and chalcedony ranges from 2.55 to 2.91.
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 Chalcedony
Chalcedony is a mineral that is widely used in jewelry making, carvings, and decorative objects. It is a member of the quartz family and is composed of microscopic crystals of quartz that are arranged in a fibrous or microcrystalline structure. The mineral is typically translucent or opaque and can come in a range of colors, including white, gray, blue, brown, and red. Chalcedony is often found in association with other minerals such as agate, jasper, and onyx.Table Comparison of Agate vs Chalcedony
| Agate (src) | Chalcedony (src) | |
|---|---|---|
| Transparency | transparent, translucent, opaque | transparent, translucent, opaque |
| Chemical Formula | SiO2 | SiO2 |
| Chemical Composition | silicon dioxide | silicon dioxide |
| Specific Gravity | 2.6, 2.64 | 2.55, 2.91 |
| Hardness | 6.5, 7 | 7 |
| Streak | white | white |
| Crystallography | hexagonal, trigonal | hexagonal, trigonal |
| Refractive Index | 1.53, 1.543 | 1.54, 1.553 |
| Hydrous | No | No |
| Colors | common: red, white sometimes: blue, gray, pink, black, brown, green, banded, orange, purple, yellow, multicolor |
common: red sometimes: blue, gray, pink, black, brown, green, white, orange, purple, yellow, band, multicolor |
| Category | chalcedony | quartz |
| Fracture | conchoidal, uneven | conchoidal |