Identification guide · Igneous Rocks
How to Identify Syenite
Syenite is typically light to medium gray, pink, or greenish, coarse-grained enough to show interlocking feldspar crystals with the naked eye, and it has an overall hardness around 6 reflecting its feldspar content. It lacks distinct rock-scale cleavage but its individual feldspar crystals show characteristic cleavage planes, and it can display a granular to slightly porphyritic texture depending on cooling history. Syenite closely resembles granite but is distinguished by its scarcity or absence of visible quartz grains, which appear glassy and clear in granite but are largely or entirely missing from syenite's mineral assemblage.
Syenite identification checklist
| Color | Gray, Pink, White, Light green | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Vitreous (feldspar crystals) | Fresh surfaces shine like glass; a dull surface usually means weathering, so chip or wet a corner. |
| Transparency | Opaque | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 5.5–6.5 | It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. |
| Fracture | Uneven | |
| Specific gravity | 2.6–2.8 | Ordinary rock-like heft (specific gravity about 2.7), similar to quartz. |
Syenite look-alikes and how to tell them apart
Both sit near Mohs 5.5–6.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Syenite vs Granodiorite →
Both sit near Mohs 5.5–6.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Syenite vs Granite →
Both sit near Mohs 5.5–6.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Syenite vs Monzonite →
Both sit near Mohs 5.5–6.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
Syenite identification FAQ
How can you tell if a rock is Syenite?
Check the color (gray, pink, white, and light green), the vitreous (feldspar crystals) luster, a Mohs hardness of 5.5–6.5. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Syenite?
Syenite has a Mohs hardness of 5.5–6.5. 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 Syenite and Granodiorite?
Syenite (Mohs 5.5–6.5, vitreous (feldspar crystals) luster) and Granodiorite (Mohs 6–7, vitreous to dull (mixed mineral grains) luster) look alike, but hardness, streak and heft usually separate them. See the full Syenite vs Granodiorite comparison for a side-by-side table.
Is Syenite worth anything?
Entry-level Syenite specimens sell for around $1, typical collector pieces about $10, and premium examples $75 or more depending on size, quality and locality.
What color is Syenite?
Syenite is most often gray, pink, white, and light green. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
