Larvikite is a light to dark grey igneous rock from the area around Larvik in southern Norway, containing large feldspar crystals that flash blue-silver when light strikes them at the right angle. That shimmer comes from light refraction within the fine lamellae of the feldspar — the effect is called schiller, or labradorescence.
Trade names and a misconception
Larvikite is sold commercially as Blue Pearl (the lighter variety) and Emerald Pearl (the darker, greenish-black variety). Both are almost universally called “granite” — in the worktop trade that word has become a catch-all for any hard, polished stone.
Geologically it is wrong. Larvikite is a monzonite: a plutonic rock consisting almost entirely of feldspar, with virtually no quartz. True granite, by definition, is quartz-rich. The distinction is more than pedantry: quartz largely governs scratch resistance, and the mineralogy governs how the stone responds to cleaning products.
Properties
Hard, dense and with low water absorption, and therefore frost resistant in a north-west European climate. It takes an excellent polish — and that is functional, because the schiller effect only really comes alive on a polished surface. On a honed or flamed finish you are left with a uniformly grey stone.
Application
Cladding and plinths on bank, office and retail buildings, polished shopfronts, window sills, worktops, floor tiles and memorials.
Points to watch:
- Polished is slippery. On floors, stairs and outdoors, specify honed, sandblasted or flamed instead, for slip resistance. Accept that the shimmer will largely disappear.
- Fix with stainless steel. As a cladding panel on anchors: ordinary steel rusts, expands and splits the panel from the anchor hole outwards. Stainless is not a luxury here.
- Cleaning. Avoid strongly acidic limescale removers and abrasive products on a polished surface. Test any product on an inconspicuous area first.
- Colour varies by block. Larvikite varies considerably in crystal size and tone. Order a facade or a continuous floor from a single batch, and dry-lay the slabs before fixing them for good.
Related terms
- Natural stone
- Granite
- Plutonic rock
- Cladding
- Quartz
- Slip resistance
Want to know more about building terms? Take a look at our knowledge base on fredsdiyplans.com.