444 SYSTEMATIC DESCRIPTION OF PRECIOUS STONES 



crevices and veins in this limestone. The greater the depth of the excavation in this 

 deposit the more abundant and finer in quality does the lapis- lazuli appear to be. The 

 workings cover an area of 7000 square feet, and, as nodules of lapis-lazuli, weighing as much 

 as 3 poods (108 pounds) are found in the Malaya Bistraya, and pebbles of the same kind 

 in the Turluntay, a tributary stream, it is probable that the deposit is still more extensive. 

 Here and there a little sulphur is found in association with the mineral, and on the 

 Malaya Bistraya stones of various shades of dark green are found in addition to the 

 blue variety. 



Lastly, lapis-lazuli is found in abundance in the Chilian Andes. According to 

 Philippi, the locality is in the Cordillera of Ovalle, only a few cuadras away from the main 

 road leading to the Argentine provinces ; it lies at the sources of the Cazadores and Vias, 

 two small tributary streams of the Rio Grande, at only a little distance from the watershed, 

 but still on Chilian soil. The mineral, which is associated with iron-pyrites, occurs in 

 blocks of various sizes in a thick bed of white and grey limestone, which rests on clay-slates 

 and is itself overlain by another bedded rock rich in iron-ore and garnet. This latter bed 

 underlies granite, which forms the upper part of the mountain. The weathering of these 

 rocks has given rise to a small plain of secondary deposits consisting of pebbles of granite, 

 slate, and iron-ore, and among these are found a few loose fragments of lapis-lazuli. The 

 Chilian lapis-lazuli is mined in some quantity ; but it is pale blue in colour, often tinged 

 with green and disfigured by white patches, so that it is much less valuable than material 

 from the Asiatic deposits. 



Small quantities of earthy lapis-lazuli are found in the ejected blocks of crystalline 

 limestone of Monte Somma, the old crater of Vesuvius ; also in the blocks of limestone 

 included in the volcanic tuff of the Albanian Hills, near Rome. Since the material is 

 unsuitable for use as a gem these occurrences require no further comment beyond stating 

 that here also, as in all other cases, the mineral is a product of the contact-metamorphism 

 of limestone. 



Among the interesting minerals brought from the ruby-earths of Burma are great 

 blocks of lapis-lazuli. These are of two varieties : in one the quantity of the blue mineral is 

 so great that the rock-masses have a deep indigo tint, while in the other there is a white 

 ground-mass speckled with blue. 



Lajiis-lazuli was highly esteemed by the ancients and was often engraved and cut in 

 bas-relief. It is still held in esteem and is used for ring-stones, brooches, and for similar 

 purposes, not only in Western countries but also in the Orient and China. Since the beauty 

 of the stone depends upon its blue colour, portions for cutting are chosen with a view to 

 obtaining stones as uniformly coloured as possible. The stone is cut with a plane or 

 slightly curved surface, facets being quite ineffective on account of the complete opacity of 

 the mineral. 



Lapis-lazuli is not now as valuable as it once was. The price of a stone depends on 

 its size, and on the purity, uniformity, and depth of its colour ; a stone with none of these 

 qualities is almost worthless. Pure, azure-blue lapis-lazuli is the most valuable ; the 

 presence of white specks and patches detracts considerably from its value, but less so if they 

 are distributed quite uniformly and regularly. Pale blue and greenish-blue lapis-lazuli is 

 worth but very little. 



The rough material used for cutting is usually in small fragments, which are sold by 

 the kilogram. Pieces of the size of a nut are common ; if of the best quality they are worth 

 ^5 per kilogram. Larger pieces of equally fine quality will fetch in the European markets 

 as much as £9,5 or £30 per kilogram. 



