Blue King

Über Blue King

Blue King is a nepheline syenite (foyaite) quarried around Solwezi in the North-Western Province of Zambia, near the border with the Democratic Republic of Congo. The stone's distinctive deep blue colour is attributed to its high sodalite content — a characteristic of alkaline plutonic rocks that gives the stone a vivid, near-electric blue background with dark matrix and occasional lighter mineral patches. DNSA (Stein 4140) provides the authoritative classification and technical data: density 2560 kg/m³, compressive strength 184 MPa, abrasion resistance 3.12 cm³/50cm² (Italian norm), thermal expansion 1.35 mm/m/100K. The stone is frost-resistant but acid-sensitive — the nepheline (feldspathoid) mineralogy reacts with acids, meaning it should not be used in aggressive chemical environments. Critical application note from DNSA: polished Blue King is not durable outdoors; exterior use requires a non-polished finish (flamed, brushed, or honed). SC corroborates the Zambian origin with density range 2560–2640 kg/m³ and compressive strength range 160–184 MPa. Also traded as Karubwe Granite (from the Karubwe quarry) and Sienite Blu in Italian markets.