{"id":7824,"date":"2021-04-08T15:55:11","date_gmt":"2021-04-08T10:25:11","guid":{"rendered":"https:\/\/gjepc.org\/solitaire\/?p=7824"},"modified":"2021-04-08T15:55:13","modified_gmt":"2021-04-08T10:25:13","slug":"new-emerald-locality-in-southern-california","status":"publish","type":"post","link":"https:\/\/gjepc.org\/solitaire\/new-emerald-locality-in-southern-california\/","title":{"rendered":"New Emerald Locality in Southern California"},"content":{"rendered":"\n

Located about 60 miles east of San Diego, a new emerald deposit has been discovered in the Julian Mining District (figure 1). This area is known for pegmatite mines and hydrothermal mineral deposits; however, none of those are known to have produced emeralds to date. The emeralds (example shown in figure 2) were all collected by author RE and son Bruce Edley near the surface and are embedded in a biotite schist host rock. Most of the recovered single crystals have a translucent dark green color and inclusions, and they are typically smaller than 2 cm. A few light-colored green beryl crystals have been recovered from a nearby pegmatite. Their formation was likely correlated with metamorphic and hydrothermal processes associated with regional tectonism.<\/p>\n\n\n\n

\"The
Figure 2. An example of an emerald cluster found in a new deposit in Julian, California. Specimen size is 20 \u00d7 10 \u00d7 9 mm. Photo by Myke Clarkson.<\/figcaption><\/figure><\/div>\n\n\n\n

Samples were analyzed at the Natural History Museum of Los Angeles County and sent to GIA for species confirmation using laser ablation\u2013inductively coupled plasma\u2013mass spectroscopy (LA-ICP-MS). We performed Raman and X-ray fluorescence (XRF) hyperspectral mapping and powder X-ray diffraction (not shown)\u2008to determine mineralogy and elemental composition. Raman analysis on a polished pill-shaped gem (figure 3, left)\u2008identified beryl and quartz to confirm our observation of the rare combination of emerald and citrine. Raman further identified dolomite and hematite inclusions. XRF element maps (figure 3, right) show silicon (Si), chromium (Cr), magnesium (Mg), iron (Fe), aluminum (Al), and holmium (Ho) content. Of the approximately 425 carats of emeralds that have been recovered, about 5\u201310% contain macro-citrine inclusions, representing a unique aspect of this deposit.<\/p>\n\n\n\n

\"\"
Figure 3. Left: A 3.16 ct polished pill-shaped emerald, seen in transmitted light, was one of the best examples of emerald with citrine from this locality. Photo by Aaron Celestian. Right: Element maps of the outlined area on the specimen. Brighter areas indicate higher concentrations.<\/figcaption><\/figure><\/div>\n\n\n\n

The distribution of trace elements in the pill-shaped emerald indicates a complex series of events. The emerald is cross-cut by a layer of citrine. Half of the gem is enriched in trace holmium (below the citrine), where holmium is inversely correlated with manganese. Chromium-rich areas run perpendicular to the citrine, but align on either side of the citrine, suggesting that the emerald formed as a single crystal. The patterns of holmium and manganese hint toward secondary geochemical processes that may be related to later citrine emplacement, though the origin of these processes is unknown. The unusual mineral associations and elemental distribution demonstrate the geologic complexity of the deposit, and further work is needed to unravel its full history.<\/p>\n\n\n\n

This\u00a0article<\/a>\u00a0is republished with permission from the Gemological Institute of America (GIA).<\/p>\n","protected":false},"excerpt":{"rendered":"

Located about 60 miles east of San Diego, a new emerald deposit has been discovered in the Julian Mining District (figure 1). This area is known for pegmatite mines and hydrothermal mineral deposits; however, none of those are known to have produced emeralds to date. The emeralds (example shown in figure 2) were all collected…<\/p>\n","protected":false},"author":1,"featured_media":7827,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[95,100],"tags":[],"thb-sponsors":[],"class_list":["post-7824","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-coloured-gemstones","category-in-focus"],"acf":[],"yoast_head":"\nNew Emerald Locality in Southern California - Solitaire magazine is a International jewellery magazine - India\u2019s leading B2B gem and jewellery magazine<\/title>\n<meta name=\"robots\" content=\"index, follow\" \/>\n<meta name=\"googlebot\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<meta name=\"bingbot\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/gjepc.org\/solitaire\/new-emerald-locality-in-southern-california\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"New Emerald Locality in Southern California - Solitaire magazine is a International jewellery magazine - India\u2019s leading B2B gem and jewellery magazine\" \/>\n<meta property=\"og:description\" content=\"Located about 60 miles east of San Diego, a new emerald deposit has been discovered in the Julian Mining District (figure 1). 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