Identification guide · Minerals
How to Identify Erythrite
Erythrite is identified almost entirely by its striking pink to purplish-red color, occurring as earthy crusts, radiating needle-like crystals, or small crystalline sprays with a pearly to vitreous luster and a paler pink streak. Its hardness of 1.5 to 2.5 makes it soft enough to scratch with a fingernail in its earthy form, and it is typically found as a thin surface coating rather than large crystals. Its color alone, distinct from nearly every other common secondary mineral, generally prevents confusion with anything except its nickel-bearing chemical cousin, annabergite, which is green rather than pink.
Erythrite identification checklist
| Color | Pink, Crimson red, Purple-red | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Vitreous, pearly on cleavage, silky | Fresh surfaces shine like glass; a dull surface usually means weathering, so chip or wet a corner. |
| Transparency | Transparent to translucent | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 1.5–2.5 | A fingernail (Mohs 2.5) scratches it easily. |
| Streak | Pale pink to pale red | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Perfect, one direction | |
| Fracture | Sectile | |
| Specific gravity | 3.06–3.18 | Heavier than it looks (specific gravity about 3.12). |
| Crystal system | Monoclinic |
Erythrite look-alikes and how to tell them apart
Calcite is harder (Mohs 3) than Erythrite (Mohs 1.5–2.5), so Calcite will scratch Erythrite and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Erythrite vs Calcite →
Quartz is harder (Mohs 7) than Erythrite (Mohs 1.5–2.5), so Quartz will scratch Erythrite and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Erythrite vs Quartz →
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. Erythrite vs Andalusite →
Anhydrite is harder (Mohs 3–3.5) than Erythrite (Mohs 1.5–2.5), so Anhydrite will scratch Erythrite and not the other way round. A fingernail (Mohs 2.5) scratches it easily.
Erythrite identification FAQ
How can you tell if a rock is Erythrite?
Check the color (pink, crimson red, and purple-red), the vitreous, pearly on cleavage, silky luster, a Mohs hardness of 1.5–2.5 and a pale pink to pale red streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Erythrite?
Erythrite has a Mohs hardness of 1.5–2.5. A fingernail (Mohs 2.5) scratches it easily.
What is the difference between Erythrite and Calcite?
Erythrite (Mohs 1.5–2.5, vitreous, pearly on cleavage, silky luster) and Calcite (Mohs 3, vitreous luster) look alike, but hardness, streak and heft usually separate them. See the full Erythrite vs Calcite comparison for a side-by-side table.
Is Erythrite worth anything?
Entry-level Erythrite specimens sell for around $2, typical collector pieces about $20, and premium examples $150 or more depending on size, quality and locality.
What color is Erythrite?
Erythrite is most often pink, crimson red, and purple-red. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
