Identification guide · Minerals
How to Identify Cinnabar
Cinnabar displays a distinctive scarlet to brick-red or brownish-red color with an adamantine to dull luster and a diagnostic red streak that immediately sets it apart from most other minerals. It is notably soft at a hardness of 2 to 2.5, has perfect cleavage in one direction, and is unusually dense for a non-metallic-looking mineral due to its high mercury content. It can superficially resemble realgar or red hematite, but cinnabar's red streak differs from hematite's reddish-brown streak, and its much greater density and softness distinguish it from the arsenic sulfide realgar.
Cinnabar identification checklist
| Color | Red, Brownish red, Gray where tarnished | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Adamantine to dull/earthy | Fresh surfaces shine like glass; a dull surface usually means weathering, so chip or wet a corner. |
| Transparency | Transparent to opaque | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 2–2.5 | A fingernail (Mohs 2.5) scratches it easily. |
| Streak | Scarlet red | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Perfect prismatic | |
| Fracture | Uneven to subconchoidal | Broken surfaces show smooth, curved, shell-like scoops. |
| Specific gravity | 8.0–8.2 | Very heavy, metallic heft (specific gravity about 8.1). |
| Crystal system | Trigonal |
Cinnabar look-alikes and how to tell them apart
Baryte is harder (Mohs 3–3.5) than Cinnabar (Mohs 2–2.5), so Baryte will scratch Cinnabar and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Cinnabar vs Baryte →
Both sit near Mohs 2–2.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Cinnabar vs Calcite →
Andalusite is harder (Mohs 6.5–7.5) than Cinnabar (Mohs 2–2.5), so Andalusite will scratch Cinnabar and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Cinnabar vs Andalusite →
Both sit near Mohs 2–2.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
Cinnabar identification FAQ
How can you tell if a rock is Cinnabar?
Check the color (red, brownish red, and gray where tarnished), the adamantine to dull/earthy luster, a Mohs hardness of 2–2.5 and a scarlet red streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Cinnabar?
Cinnabar has a Mohs hardness of 2–2.5. A fingernail (Mohs 2.5) scratches it easily.
What is the difference between Cinnabar and Baryte?
Cinnabar (Mohs 2–2.5, adamantine to dull/earthy luster) and Baryte (Mohs 3–3.5, vitreous, pearly on cleavage luster) look alike, but hardness, streak and heft usually separate them. See the full Cinnabar vs Baryte comparison for a side-by-side table.
Is Cinnabar worth anything?
Entry-level Cinnabar 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 Cinnabar?
Cinnabar is most often red, brownish red, and gray where tarnished. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
