Identification guide · Minerals
How to Identify Cuprite
Cuprite is identified by its characteristic deep red to reddish-brown color, adamantine to submetallic luster, and brownish-red streak, a combination not shared by many other minerals. It has a hardness of 3.5 to 4, is somewhat brittle, shows poor cleavage, and breaks with a conchoidal to uneven fracture. It occurs as cubic or octahedral crystals, in massive form, or as tufted, hair-like chalcotrichite. Cuprite is sometimes mistaken for hematite or cinnabar, but its distinct red streak and association with other copper minerals usually settle the question.
Cuprite identification checklist
| Color | Red, Dark red, Nearly black | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Adamantine to submetallic or earthy | Turn it under a lamp: a true metallic shine reflects like polished metal and stays opaque at thin edges. |
| Transparency | Transparent to nearly opaque | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 3.5–4 | A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. |
| Streak | Brownish red | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Poor, indistinct octahedral | |
| Fracture | Conchoidal to uneven | Broken surfaces show smooth, curved, shell-like scoops. |
| Specific gravity | 6.0–6.15 | Very heavy, metallic heft (specific gravity about 6.075). |
| Crystal system | Cubic |
Cuprite look-alikes and how to tell them apart
Cuprite is harder (Mohs 3.5–4) than Copper (Mohs 2.5–3), so Cuprite will scratch Copper and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not. Cuprite vs Copper →
Hematite is harder (Mohs 6) than Cuprite (Mohs 3.5–4), so Hematite will scratch Cuprite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Cuprite vs Hematite →
Both sit near Mohs 3.5–4, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Cuprite vs Calcite →
Both sit near Mohs 3.5–4, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
Cuprite identification FAQ
How can you tell if a rock is Cuprite?
Check the color (red, dark red, and nearly black), the adamantine to submetallic or earthy luster, a Mohs hardness of 3.5–4 and a brownish red streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Cuprite?
Cuprite has a Mohs hardness of 3.5–4. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
What is the difference between Cuprite and Copper?
Cuprite (Mohs 3.5–4, adamantine to submetallic or earthy luster) and Copper (Mohs 2.5–3, metallic luster) look alike, but hardness, streak and heft usually separate them. See the full Cuprite vs Copper comparison for a side-by-side table.
Is Cuprite worth anything?
Entry-level Cuprite 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 Cuprite?
Cuprite is most often red, dark red, and nearly black. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
