Ovalle
Ovalle
The Coquimbo Region town and the Chilean lapis lazuli source
Ovalle is the principal town of the Limarí Province in the Coquimbo Region of north-central Chile, situated in the semi-arid pre-Andean foothills approximately 400 kilometres north of Santiago. The town is the trade and administrative centre nearest the Chilean lapis lazuli deposits, and Ovalle in the gemmological literature is essentially shorthand for those deposits and for the broader Chilean lapis trade that has supplied an alternative source to Afghan material since the mid-twentieth century.
Geological setting
The Chilean lapis lazuli deposits sit at roughly 3,500 metres altitude in the Andes east of Ovalle, principally at the Flor de los Andes mine on the upper Cazadero River and at related workings in the Las Vacas valley. The deposits are skarns developed at the contact between Cretaceous limestone and intrusive granitic and dioritic bodies, with lazurite forming in the contact metamorphic zone alongside the more familiar associated minerals — pyrite, calcite, sodalite, hauyne, and diopside. The geological setting is broadly comparable to the Sar-i-Sang deposits of Badakhshan, although the Chilean material is on average lighter in colour with a higher calcite content.
Material character
Chilean lapis from the Ovalle source typically runs in a medium royal-blue body colour with substantial white calcite veining and a moderate to high pyrite content. The deepest, most uniformly coloured material approaches but does not reach the saturation of the finest Afghan lapis, and the trade convention places Chilean lapis in the second tier on body-colour grounds. The pyrite content, however, is often more attractively distributed than in lower-grade Afghan material, with fine flecking that polishes to a bright golden lustre against the blue.
Hardness is 5 to 5.5 on the Mohs scale, specific gravity around 2.7 to 2.9, refractive index approximately 1.50, and the body shows the characteristic absorption pattern of lazurite under filter and spectroscope. The material takes a high polish on the calcite-poor zones; calcite-rich material polishes less evenly and is generally graded as the lower commercial tier.
History and the modern trade
Lapis lazuli has been recovered from the Andean deposits since pre-Columbian times, with finds documented in archaeological contexts at the Inca and pre-Inca sites of north-central Chile. Modern commercial production began in the mid-twentieth century, with the Flor de los Andes mine becoming the principal commercial operation. Chile is now the world's second-largest source of lapis lazuli by volume, after Afghanistan. Production from Ovalle and the related workings is exported principally through the Chilean cutting trade and through European wholesalers, with the bulk of the material entering the cabochon and ornamental-object markets at moderate price points.
In the trade
Chilean lapis trades at a price discount of approximately thirty to fifty percent below comparable-quality Afghan material on a body-colour basis, with the discount varying with the relative calcite and pyrite content. The material is widely used for cabochons, beads, carvings, and inlay work, and is the standard commercial source where price-point considerations dominate. Origin determination between Chilean and Afghan material is sometimes possible by trace-element analysis but is rarely commercially performed; the trade relies on visual evaluation of body colour, calcite distribution, and pyrite character.
Ovalle is also a market and finishing centre for the regional cutting trade, with workshops in the town producing finished cabochons, beads, and ornamental objects from rough that arrives from the Andean mines. Tourism plays a role in the local market for finished pieces.
Care
Lapis lazuli is sensitive to acids, ultrasonic and steam cleaning, and prolonged solvent exposure. Cleansing should be by mild soap and warm water with a soft brush. Some Chilean lapis is wax-impregnated to improve polish and to seal calcite zones; impregnation is detectable by laboratory examination and should be disclosed at the point of sale.