Comparison · Minerals
Andalusite vs Erythrite
Andalusite and Erythrite are easy to confuse because both are minerals. Andalusite is harder (Mohs 6.5–7.5) than Erythrite (Mohs 1.5–2.5), so Andalusite will scratch Erythrite and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Andalusite and Erythrite
- Andalusite is harder (Mohs 6.5–7.5) than Erythrite (Mohs 1.5–2.5), so Andalusite will scratch Erythrite and not the other way round. A fingernail (Mohs 2.5) scratches it easily.
- Streak color differs: Andalusite leaves a white streak on unglazed porcelain, Erythrite leaves pale pink to pale red.
- They overlap in red and pink, but Andalusite also comes in brown, green, and gray and Erythrite also comes in purple.
- Well-formed crystals give it away: Andalusite is Orthorhombic, Erythrite is Monoclinic.
Andalusite vs Erythrite properties
| Property | Andalusite | Erythrite |
|---|---|---|
| Type | Minerals | Minerals |
| Mohs hardness | 6.5–7.5 | 1.5–2.5 |
| Luster | Vitreous | Vitreous, pearly on cleavage, silky |
| Streak | White | Pale pink to pale red |
| Transparency | Transparent to translucent | Transparent to translucent |
| Specific gravity | 3.13–3.21 | 3.06–3.18 |
| Crystal system | Orthorhombic | Monoclinic |
| Common colors | Reddish brown, Olive green, Gray, Pink | Pink, Crimson red, Purple-red |
| Rarity | common | common |
| Typical specimen value | $2–$150+ | $2–$150+ |
Which is more valuable?
Typical specimens of Andalusite and Erythrite trade in a similar range, around $20.
About Andalusite
Andalusite is an aluminum silicate, Al2SiO5, and one of three natural polymorphs sharing that exact formula along with kyanite and sillimanite. It crystallizes in the orthorhombic system as stout, nearly square prisms formed under low-pressure, moderate-temperature metamorphism. Its variety chiastolite, which displays a dark cross pattern in cross-section, makes it one of the more recognizable metamorphic minerals to casual collectors.
About Erythrite
Erythrite is a hydrous cobalt arsenate, Co3(AsO4)2 8H2O, crystallizing in the monoclinic system with a vivid pink to crimson color that made it a prized prospecting clue. Long nicknamed cobalt bloom or cobalt flower, it forms as a secondary mineral where cobalt-bearing ores have been exposed to oxidizing, weathering conditions. Its bright coloring and soft, often earthy texture make it easy to spot even in small amounts.
Andalusite vs Erythrite FAQ
Is Andalusite the same as Erythrite?
No. Both are minerals, but they are distinct species with different hardness, streak or luster. Andalusite is harder (Mohs 6.5–7.5) than Erythrite (Mohs 1.5–2.5), so Andalusite will scratch Erythrite and not the other way round. A fingernail (Mohs 2.5) scratches it easily.
How can you tell Andalusite from Erythrite?
Andalusite is harder (Mohs 6.5–7.5) than Erythrite (Mohs 1.5–2.5), so Andalusite will scratch Erythrite and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Streak color differs: Andalusite leaves a white streak on unglazed porcelain, Erythrite leaves pale pink to pale red. They overlap in red and pink, but Andalusite also comes in brown, green, and gray and Erythrite also comes in purple.
Which is harder, Andalusite or Erythrite?
Andalusite is harder: Mohs 6.5–7.5 against Mohs 1.5–2.5 for Erythrite.
Which is more valuable, Andalusite or Erythrite?
Typical specimens of Andalusite and Erythrite trade in a similar range, around $20.
