Identification guide · Minerals
How to Identify Almandine
Almandine typically appears deep red to reddish-brown or nearly black, with a vitreous to slightly resinous luster and a white streak despite its dark body color. It has a hardness of about 7 to 7.5, no true cleavage but conchoidal to uneven fracture, and commonly forms rounded rhombic dodecahedra or trapezohedra in schist. It is denser than most look-alike red minerals, which helps separate it from spinel, ruby, or andradite garnet; the lack of cleavage and rounded crystal shape distinguish it from staurolite.
Almandine identification checklist
| Color | Deep red, Reddish brown, Purplish red, Black | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Vitreous to resinous | 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 | 7–7.5 | It scratches glass and a steel knife and cannot be scratched by a steel file. |
| Streak | White | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | None (indistinct parting) | |
| Fracture | Conchoidal to uneven | Broken surfaces show smooth, curved, shell-like scoops. |
| Specific gravity | 3.9–4.3 | Heavier than it looks (specific gravity about 4.1). |
| Crystal system | Cubic |
Extra tests for Almandine
Glass check. Almandine shares a glassy luster and conchoidal fracture with man-made glass. Glass sits near Mohs 5.5 and often contains round gas bubbles, so a hardness test and a hand lens separate them.
Almandine look-alikes and how to tell them apart
Both sit near Mohs 7–7.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Almandine vs Andradite →
Both sit near Mohs 7–7.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Almandine vs Hessonite →
Both sit near Mohs 7–7.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Almandine vs Grossular →
Both sit near Mohs 7–7.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
Almandine identification FAQ
How can you tell if a rock is Almandine?
Check the color (deep red, reddish brown, purplish red, and black), the vitreous to resinous luster, a Mohs hardness of 7–7.5 and a white streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Almandine?
Almandine has a Mohs hardness of 7–7.5. It scratches glass and a steel knife and cannot be scratched by a steel file.
What is the difference between Almandine and Andradite?
Almandine (Mohs 7–7.5, vitreous to resinous luster) and Andradite (Mohs 6.5–7, vitreous to resinous/adamantine luster) look alike, but hardness, streak and heft usually separate them. See the full Almandine vs Andradite comparison for a side-by-side table.
Is Almandine worth anything?
Entry-level Almandine 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 Almandine?
Almandine is most often deep red, reddish brown, purplish red, and black. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
