Blue Pectolite from the Dominican Republic

Abstract

Blue pectolite from the Dominican Republic, also known by the trade name Larimar, has recently entered the U.S. market. Large quantities of this attractive ornamental stone have been found i n cavities and veins of altered basalt. Most of the gemologiccil properties are consistent with those previously reported for pectolite; the cause of color in this material is believed to be related to the presence of small amounts of Cu2+. The color appears to be stable to light, but does react to irradiation and to the heat of a jeweler's torch. It is easily separated from similar-appearing materials.

Larimar – a unique pectolite rock from the Dominican Republic

“…Other minerals, such as calcite, natrolite, chalcedony, hematite, chalcocite, crystal formations, and occasionally hematite dendrites, coexist with pectolite and are located along the border fillings (Woodruff & Fritsch 1989). Apatite, sphene, prehnite, danburite and datolite were also found in these heterogeneous masses (Fuertes Marcuello & Garcia Guinea 1990).…”

“…The origin of the larimar colour is still not obvious. It has been associated with the presence of copper coming from copper sulphide (Woodruff & Fritsch 1989). Bente et al (1991) suggested that vanadium was the cause of the colouration and the authors did not exclude the presence of other possible elements like Fe, Ti, Cr, Co, or Ni.…”

“…Using a thermoluminescence dating, in light blue and blue pectolite were confirmed trace amounts of manganese (Sullasi et al 2010). Woodruff & Fritsch (1989) are not excluded a manganese as a colouring agent. Espi & Borrego suggested in 2008 that organic matter might have been related to the larimar coloration.…”

X-ray Photoelectron Spectroscopy study of so-called “Larimar”, blue pectolite from the Dominican Republic

“…It has been reported that the pectolite contains small particles of native copper and red plumes of iron [1,2,5,6]. Also mentioned is the presence of small amounts of Mn [3], Cr, and V [4] as possible sources for the colour .…”

“…A blue pectolite (NaCa2Si3O8)(OH) , known under the trade-name Larimar, is found in the Sierra de Baoruco, Barahona Province, southern Dominican Republic [1,2]. Pectolite is a triclinic inosilicate with a structure similar to that of wollastonite [3].…”