AllMineralsRock
Aragonite Vs. Chalcedony
Aragonite is a popular mineral composed of calcium carbonate.[1] Chalcedony is a very popular gemstone and its chemical composition is silicon dioxide.[2]
Quick Facts on Differences of Aragonite and Chalcedony
For a quick recap of the differences aragonite and chalcedony:- While both aragonite and chalcedony can be hexagonal, in terms of crystallography, aragonite can be orthorhombic and chalcedony can be trigonal.
- For chemical formulas, aragonite is CaCO3 while chalcedony is SiO2.
- While both aragonite and chalcedony can be dull or vitreous, in terms of luster, aragonite can be resinous and chalcedony can be waxy.
- Aragonite can be commonly green while chalcedony can be commonly red.
- Aragonite's rarity is more rare than chalcedony.
-
Aragonite's hardness is lower than chalcedony - aragonite ranges from 3.5 to 4 and chalcedony is 7 on the Moh's scale.
- Aragonite can be scratched by the average knife blade (4.5), glass (5.5) or quartz (7) while chalcedony can not be.
- Aragonite's specific gravity is higher than chalcedony - aragonite ranges from 2.93 to 2.947 and chalcedony ranges from 2.55 to 2.91.
Quick Facts on Similarities of Aragonite and Chalcedony
The similarities of aragonite and chalcedony include:- Aragonite and chalcedony both can be opaque, translucent or transparent.
- Aragonite and chalcedony both streak white.
Summary of Aragonite
Aragonite is a mineral that is commonly found in sedimentary rocks such as limestone, dolomite, and marble. It is a polymorph of calcium carbonate, which means that it has the same chemical formula as calcite but a different crystal structure. Aragonite is named after the Aragon region in Spain where it was first discovered.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 Aragonite vs Chalcedony
| Aragonite (src) | Chalcedony (src) | |
|---|---|---|
| Transparency | transparent, translucent, opaque | transparent, translucent, opaque |
| Chemical Formula | CaCO3 | SiO2 |
| Chemical Composition | calcium carbonate | silicon dioxide |
| Specific Gravity | 2.93, 2.947, 2.95, 3 | 2.55, 2.91 |
| Hardness | 3.5, 4 | 7 |
| Streak | white | white |
| Crystallography | orthorhombic, hexagonal | hexagonal, trigonal |
| Refractive Index | 1.53, 1.685 | 1.54, 1.553 |
| Hydrous | No | No |
| Colors | common: green sometimes: red, blue less common: gray, pink, brown, white, orange, purple, yellow, lavender, colorless |
common: red sometimes: blue, gray, pink, black, brown, green, white, orange, purple, yellow, band, multicolor |
| Category | carbonate | quartz |
| Fracture | subconchoidal | conchoidal |