Identification guide · Halide Minerals
How to Identify Sylvite
Sylvite is usually colorless, white, and red with a vitreous luster and is transparent. It has a Mohs hardness of 2. A fingernail (Mohs 2.5) scratches it easily. Its streak is white. It is most often confused with Anhydrite, Gypsum, and Halite; the tests below separate them.
Sylvite identification checklist
| Color | Colorless, White, Red, Pink, Bluish | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Vitreous | Fresh surfaces shine like glass; a dull surface usually means weathering, so chip or wet a corner. |
| Transparency | Transparent | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 2 | A fingernail (Mohs 2.5) scratches it easily. |
| Streak | White | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Perfect cubic | |
| Fracture | Uneven | |
| Specific gravity | 1.99 | Noticeably light in the hand for its size (specific gravity about 1.99). |
| Crystal system | Cubic |
Sylvite look-alikes and how to tell them apart
Anhydrite is harder (Mohs 3–3.5) than Sylvite (Mohs 2), so Anhydrite will scratch Sylvite and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Sylvite vs Anhydrite →
Both sit near Mohs 2, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Sylvite vs Gypsum →
Both sit near Mohs 2, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Sylvite vs Halite →
Both sit near Mohs 2, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
Field tips
- Look for cubic crystals or granular masses with perfect cubic cleavage and low hardness near 2.
- Sylvite tastes distinctly bitter, which separates it from salty-tasting halite.
- Very low density and red or pink coloring from hematite inclusions are additional clues.
Sylvite identification FAQ
How can you tell if a rock is Sylvite?
Check the color (colorless, white, red, and pink), the vitreous luster, a Mohs hardness of 2 and a white streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Sylvite?
Sylvite has a Mohs hardness of 2. A fingernail (Mohs 2.5) scratches it easily.
What is the difference between Sylvite and Anhydrite?
Sylvite (Mohs 2, vitreous luster) and Anhydrite (Mohs 3–3.5, vitreous, pearly on cleavage surfaces luster) look alike, but hardness, streak and heft usually separate them. See the full Sylvite vs Anhydrite comparison for a side-by-side table.
Is Sylvite worth anything?
Entry-level Sylvite specimens sell for around $5, typical collector pieces about $30, and premium examples $180 or more depending on size, quality and locality.
What color is Sylvite?
Sylvite is most often colorless, white, red, and pink. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
