Russian Gemstones Encyclopedia

Vladimir Bukanov. Russian Gemstones Encyclopedia



PECTOLITE (Pektolith—Pectolite—ѕектолит) (von Kobell, Fr. 1828), from Gk. “pektos” – well put together, alluding to its compact structure; and “lithos” – stone.

Composition & Properties. Silicate – Ca2Na[Si3O8OH], subclass chain silicate, triclinic system. Hardness 4.5-5. Density 2.8. Glass luster to pearl one, silk one in aggregates. Perfect cleavage in two directions. Fragile. Pectolite forms fibrous and radial-rayed aggregates and solid porcelain-like accumulations – pectolite jade. Color: white, gray, and because of the admixture of copper – light blue and green. It can be translucent as gem-quality chrysocolla, or non-transparent as green variscite. When polished, parallel-fibrous aggregates display the effect of cat’s-eye. The content of pectolite jade is uneven, it contains many admixtures, which strengthen its hardness to 7. Varieties of pectolite are known: with the admixture of MgO up to 5% – walkerite, in the shape of meat-red columnar aggregates; and enriched with manganese – manganpectolite, in crystals, up to 9x3x5 cm. in size and in their radial-rayed aggregates. The color of pectolite depends on inclusions of native copper and hematite.

Deposits. It is found in cavities of hydrothermal veins and in metamorphic rocks, rich with calcium. In Russia ornamental pectolite was discovered in the Polar Urals, in the southern part of the Voikaro-Synjinskiy massif, as veins up to 10 cm. thick in dikes. The second discover of this type was made in the massif Ray Iz, on the eastern slope of the Chiornaya Mt., 40 km. south from the railway station Kharp. Light bluish-greenish tone is typical to it because of inclusions of copper-nickel minerals. In the Northern Caucasus, along the Malka River, in veins among gabbro-norite, near the of Khabaz village, they discovered crystals of pectolite up to 5 cm. in cross-section. In the north of the Krasnoyarsk Region, at the deposits Odikhincha, Oktyabr’skoye, Talnakh pectolite was found as snow-white and rose crystals and radial-rayed aggregates. In the middle reaches of the Lower Tunguska River, pectolite was found in cavities among traps. In Yakutia (Sakha), in the Murun alkali massif, at the Sirenevyi Kamen’ deposit of charoite, pink-lilac potassium pectolite – miserite is found in joints with aggregates of charoite. On the North Kamchatka, in the contact of the ultra-basic Kuiulskiy massif, ornamental pectolite is represented with veins of white color, sometimes with violet and light bluish tone. After irradiation with gamma-rays this pectolite displays violet color. In the north of Sakhalin Is. they found its placers with pebbles. In Japan, on the Central Hokkaidö Is., they extract Hidaka jade, an ornamental stone composed with chromium-containing diopside with admixture of pectolite.

Pectolite as an ornamental stone at first attracted attention in 1974, after the finding of light blue variety of pectolite jade – larimar on the Haiti Is., Dominican Rep. It was discovered as massive accumulations in transformed basalts at Baoruco, Barahona Prov. There was another variety also found – red feather with inclusions of hematite. Besides, deposits of ornamental pectolite, available for cabochon cut, are known in the U.S.A.: in Alaska – bluish-green, fine-grained Alaska jade; in California, Lakes Co. – solid material of greenish-light blue color; in Arkansas, at the Magnet cove deposit – pink manganpectolite; in Connecticut and New Jersey, at the deposits Bergen Hill, Paterson, Franklin and Sterling Hill – in the shape of radial-rayed and fibrous aggregates. In Canada, at the Zetford and Jeffrey mines, near Asbestos, Québec Prov., they find white and light bluish-green columnar crystals of pectolite up to 13 cm. long, available for faceting. In Europe, pectolite was discovered in Poland, at the Mièdzyrzecze Górne deposit, near Bielsko-Biala, in the shape of veins in massive radial-rayed aggregates up to 12 cm. thick, composed with fibrous crystals of pectolite up to 6 cm. long. In Slovenia, at the Ayrshire deposit was found walkerite. Fibrous osmelith it is described in Germany at the Wolfstein deposit, in Bavaria.

Synonyms. Pectolite cat’s-eye | Natronwollastonit | Osmelith, from Gk. “osme” – smell and “litos” – a stone | Photolith | Ratholite, after the discovery location on the Rath Cape, Scotland, Great Britain | Schizolite | Table-like spar | Stellite, from Lat. “stella” – a star, after the type of its aggregates | Larimar stone | Wollastonite, mist. name.

Treatment. In viscosity pectolite is close to jadeite, it is well polished and easy colored. It makes this rock perspective as an ornamental stone. It is cut in cabochons, it is used for stone-carving for small produce. Blue pectolite is used for imitation of turquoise. Rare transparent crystals up to 5 cm. long were faceted for collection purposes.