Turquoise from Zhushan County, Hubei Province, China

Abstract

C hina has been a significant source of turquoise for decades. One area of Zhushan County in Hubei Province has produced some attractive material (e.g., figure 1), but it has been overshadowed by more productive turquoise deposits in nearby Yun County (Tu, 2000). Chinese turquoise is also known from the city of Ma'anshan in Anhui Province, Baihe County in Shaanxi Province, and the Xichuan area of Henan Province.The turquoise from Yun County is regarded as superior in quality (Ma, 1989;Qi et al., 1998; Tu, 2000). The output from Yun County between 1954 and 1999 totaled more than 800 tonnes, according to data provided by local officials, but its resources are depleting. The deposits in Zhushan County (figure 2) were found in the late 1980s, yet much is still unknown about their distribution and complex geologic formation. While the material from Zhushan County is often of high quality, with a dense texture and an attractive uniform coloration, mining activity has only recently begun.

Reflectance Spectroscopy Characteristics of Turquoise

“…Hyper-spectral imaging has been widely used in geological mapping [8][9][10][11], ore exploration [12][13][14], nature conservation [15][16][17][18], and food or drink quality analysis [19,20]. Recent studies have also used this technology to conveniently and economically examine ancient documents and archaeological artifacts [21][22][23].…”

Blue or green? turquoise–planerite species from Carico Lake Valley in Nevada, the United States: Evidence from Raman spectroscopy

“…The blue and green turquoise species filling in numerous veins intersecting the quartzites and cherts of the Valmy and Slaven Chert Formations or forming nodules on their surfaces are found abundantly in Carico Lake Valley . In the literature, some works on spectroscopic characteristics of turquoise minerals from various regions of the world, for example, Arizona, Senegal, Virginia, China, England, have been published yet . However, no one has focused on tracing differences with Raman microspectroscopy between variously coloured species coming from the same locality.…”

“…[3,4] When affected by nearsurface conditions and extended exposure to sunlight and meteoric water, turquoise weathers to clay minerals. [2] The colouring mechanisms in turquoise have been broadly discussed by Clark, [5] Huifen, [6] Foord and Taggart, [1] Crespo-Feo et al, [7] and Chen et al, [8] and these authors all agree that the blue colour is attributed to the presence of Cu 2+ being substituted by Fe 3+ in the structure of natural samples. Indeed, the colour of turquoise seems to be related to the Cu 2+ /Fe 3+ ratio, showing blue tones at higher Cu/Fe values, whereas lower ratios give greenish shades.…”

“…[9] In the literature, some works on spectroscopic characteristics of turquoise minerals from various regions of the world, for example, Arizona, Senegal, Virginia, China, England, have been published yet. [2,8,[10][11][12] However, no one has focused on tracing differences with Raman microspectroscopy between variously coloured species coming from the same locality. Hence, in our work, special attention was paid to reconstructing the origin of their colour by Raman microspectroscopy supported by microprobe and thermal analyses.…”

Raman and infrared spectroscopic study of turquoise minerals

“…Today, turquoise is popular in fine jewellery as well as in various cultures, most notably among Native Americans in the south-western United States [1,2]. The first orientation of turquoise studies allows archaeologists to investigate pre-Colombian turquoise trade structures in North America and identify or authenticate the natural sources of turquoise worldwide [3][4][5][6][7]. Various physico-chemical characteristics of turquoise were studied together with questions of turquoise provenance especially with regard to its wealth of colors (blue, green in various shades) and further properties important for its use in jewellery [8][9][10][11][12][13][14][15].…”