Jasper is a widely distributed mineral and a form of microcrystalline quartz, prized for its opaque nature and rich coloration. This silica-based material is an aggregate of fine-grained quartz or chalcedony, making it robust and durable. Green jasper is a sought-after variety, with its deep color making it desirable for lapidary work and ornamentation. The search for green jasper takes geologists and collectors to various continents, highlighting its presence in both ancient bedrock and recent deposits worldwide.
Defining Green Jasper and Its Geological Origin
Green jasper is an impure variety of silicon dioxide with a cryptocrystalline structure, meaning its quartz crystals are microscopic. The opaque green hue distinguishes it from translucent green chalcedony varieties. This color results from the inclusion of specific iron-bearing silicate minerals within the silica matrix, such as chlorite, epidote, and celadonite, which lend the stone shades ranging from olive to deep forest green.
The formation of green jasper is linked to silica-rich environments and hydrothermal activity. This process involves the precipitation of silica from hot, mineral-laden fluids that circulate through the Earth’s crust, often near volcanic activity. The fluids cause silicification as the silica deposits in fractures, veins, or replacement zones within the host rock.
Jasper can also form in sedimentary settings, notably as a component of Banded Iron Formations (BIFs). These are ancient layered rocks containing alternating bands of iron oxides and silica. The resulting material is opaque due to the incorporation of foreign materials, which can constitute up to 20 percent of the stone’s total mass.
Primary Global Sources: North and South America
The North American continent is home to distinct green jasper occurrences, particularly within the western United States. Oregon is a significant source, known for producing vivid, emerald-colored jasper in its eastern regions. Specific varieties such as Biggs Jasper and Deschutes Jasper are recognized for their fine banding and patterns, which can include green coloration.
Idaho contributes the well-known Bruneau Jasper from the Bruneau River canyon, which often features brown and cream patterns but can also exhibit green banding. Other states with notable deposits include California, Utah, Wyoming, Texas, and Montana. These deposits are often linked to the region’s extensive history of volcanic activity.
Moving south, green jasper is found across Mesoamerica and South America. Mexico is a known source of jasper, and some materials found there contain green zones. Brazil holds significant deposits, with the state of Bahia producing rich material, including a bright green variety of jasper. Lesser, yet still important, occurrences are also documented in countries like Peru and Uruguay.
Key Deposits in the Eastern Hemisphere: Asia, Africa, and Australia
The Eastern Hemisphere offers a wide array of green jasper deposits, with substantial sources in Russia and Australia. The Russian Federation contains abundant material, particularly in the Ural Mountains and Siberia. A notable location is near Lake Baikal in Siberia, which yields a range of colors from forest green to olive green. Specific finds include a blue-green jasper variety at Ettutkan Mountain, Staryi Sibay, in Bashkortostan.
In Asia, India is recognized for its high-quality green jasper, with deposits located in the Deccan Traps region. India also produces brecciated jasper, a form where fragments of the stone are naturally cemented together, which can feature green hues. Another significant Asian source is Cambodia, where recent study has detailed the mineralogy of deep green jasper found in the northeastern part of the country.
Australia is home to large, ancient green jasper deposits, particularly within the Pilbara region of Western Australia, known for their deep green coloring. The country is also the sole source of Rainforest Jasper, a material mined at Mount Hay in Central Queensland, which is commercially valued for its green color and unique patterns.
African sources also contribute to the global supply, including deposits near the Red Sea coast in Egypt. South Africa is listed among the main producers of green jasper. Zimbabwe is recognized for a rare, distinct variety of green jasper that contains high levels of chromium.
European and Lesser-Known Deposits
Europe features several historically significant sources of green jasper, though often in smaller volumes compared to global producers. Germany has notable deposits, including the Fahsel quarry in Blauenthal, Saxony, which is part of the Ore Mountains region. Jasper is also found at the Büchenberg Mine in Elbingerode, Harz, and the Juchem Quarry in Niederwörresbach.
The Czech Republic is another European country with documented jasper occurrences. In the United Kingdom, specific finds of green jasper have been noted in Wales at Ynys Llanddwyn. Lesser-known but important deposits are found in Austria, which yields a serpentine-rich green jasper, and France and Italy.
Other minor deposits of green jasper are also located globally, including:
- Canada
- Kazakhstan
- Namibia