Identification guide · Igneous Rocks
How to Identify Larvikite
Larvikite is usually dark gray, blue gray, and black with a vitreous luster and is opaque. 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 to light gray. It is most often confused with Granite, Diorite, and Gabbro; the tests below separate them.
Larvikite identification checklist
| Color | Dark gray, Blue gray, Black, Silver blue, White | 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 | Opaque | 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 to light gray | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Variable by feldspar grains | |
| Fracture | Uneven to granular | |
| Specific gravity | 2.75 | Ordinary rock-like heft (specific gravity about 2.75), similar to quartz. |
Larvikite look-alikes and how to tell them apart
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Larvikite vs Granite →
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Larvikite vs Diorite →
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Larvikite vs Gabbro →
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 dark gray to black feldspar-rich rock with blue-silver flashes.
- Larvikite is usually coarse grained and igneous, not a single mineral crystal.
- Polished surfaces show the feldspar flash much better than rough weathered surfaces.
- Do not confuse it with Labradorite; larvikite is a rock, while labradorite is a feldspar mineral.
Larvikite identification FAQ
How can you tell if a rock is Larvikite?
Check the color (dark gray, blue gray, black, and silver blue), the vitreous luster, a Mohs hardness of 6 and a white to light gray streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Larvikite?
Larvikite 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 Larvikite and Granite?
Larvikite (Mohs 6, vitreous luster) and Granite (Mohs 6.5, vitreous luster) look alike, but hardness, streak and heft usually separate them. See the full Larvikite vs Granite comparison for a side-by-side table.
Is Larvikite worth anything?
Entry-level Larvikite specimens sell for around $5, typical collector pieces about $40, and premium examples $300 or more depending on size, quality and locality.
What color is Larvikite?
Larvikite is most often dark gray, blue gray, black, and silver blue. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
