Identification guide · Silicate Minerals
How to Identify Sugilite
Sugilite is usually purple, violet, and magenta with a vitreous luster and is translucent. It has a Mohs hardness of 6. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Its streak is white. It is most often confused with Quartz, Scapolite, and Spodumene; the tests below separate them.
Sugilite identification checklist
| Color | Purple, Violet, Magenta, Pink, Brownish yellow | 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 | Translucent | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 6 | It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. |
| Streak | White | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | None | |
| Fracture | Conchoidal to uneven | Broken surfaces show smooth, curved, shell-like scoops. |
| Specific gravity | 2.74 | Ordinary rock-like heft (specific gravity about 2.74), similar to quartz. |
| Crystal system | Hexagonal |
Extra tests for Sugilite
Glass check. Sugilite 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.
Sugilite look-alikes and how to tell them apart
Quartz is harder (Mohs 7) than Sugilite (Mohs 6), so Quartz will scratch Sugilite and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Sugilite vs Quartz →
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Sugilite vs Scapolite →
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Sugilite vs Spodumene →
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
Field tips
- Look for solid, massive purple to magenta material rather than distinct crystals.
- Moderate hardness near 6, lack of cleavage, and association with manganese minerals are strong clues.
- Color can range from pale lilac to deep royal purple, so confirm rare or costly stones with proper testing.
Sugilite identification FAQ
How can you tell if a rock is Sugilite?
Check the color (purple, violet, magenta, and pink), the vitreous luster, a Mohs hardness of 6 and a white streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Sugilite?
Sugilite has a Mohs hardness of 6. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
What is the difference between Sugilite and Quartz?
Sugilite (Mohs 6, vitreous luster) and Quartz (Mohs 7, vitreous, greasy on fracture surfaces luster) look alike, but hardness, streak and heft usually separate them. See the full Sugilite vs Quartz comparison for a side-by-side table.
Is Sugilite worth anything?
Entry-level Sugilite specimens sell for around $15, typical collector pieces about $150, and premium examples $1200 or more depending on size, quality and locality.
What color is Sugilite?
Sugilite is most often purple, violet, magenta, and pink. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
