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Zircon, in its unchanged natural form appears colorless to pale yellow, or green. These colors are caused by minute quantities of thorium and uranium that replaces zircon in the crystal structure. But over the vast spans of geologic time, other forces work within the zirconium silicate crystals. The uranium and thorium inclusions emit radiation that alters the original crystal structure. A glass-like material is formed, with colors of red to brown, orange and yellow.

The mineral zircon, known as zirconium silicate, is commonly found as a minor constituent in igneous rock such as granites and some kinds of metamorphic rock. Gem quality zircon stones are usually rare. These gemstones are formed mainly in pegmatites (coarse-grained igneous rock) and in fissures. But due to weathering of the gem-bearing rocks, most zircons are found in alluvial and beach deposits.

The most prized zircon is the red gemstone, which is rare. The pure intense blue and sky blue varieties are also highly valued, while the colorless, orange, brown and yellow stones are less expensive. Many zircons on the market are heat treated, and sold as blue, golden brown or colorless stones. Colorless zircons are the best imitators of diamonds, in appearance only, with a brilliant fire that is almost as dazzling as the real thing. However, the resemblance is superficial. Zircon is a brittle stone, easily broken with a well-placed knock, due to internal stresses in the crystal caused by radiation damage and heat treatment. But despite its frail disposition, the stone is still highly valued because of its stunning beauty.

Major sources of zircon are the Chanthaburi area of Thailand, the Palin area of Cambodia and the southern part of Vietnam near the Cambodian border, where gemstones are found in alluvial deposits. Bangkok is well-known as a major center for processing zircons, where everything from heat treatment, cutting and marketing is carried out. Another important source is Sri Lanka, well known for a colorless variety of zircon called the 'Matura diamond'. The gemstones are also found in Burma, France, Norway, Australia and Canada.

The hyacinth and jacinth, reddish-brown and orange-red varieties of zircon, were a favorite stone of ancient Arabs and was even mentioned in the famed book, 'Arabian Nights'.

Green zircon was among the stones of the 'Kalpa Tree' of the Hindu religion, where it represented the tree's foliage. This tree was a symbolic offering to the gods. Hindu poets of the 19th century described it as a glowing ensemble of precious stones that also included sapphires, diamonds and topaz.

Saco Valley Gem and Mineral Club 3^rd Thursday of each month at the Albany,

NH Town Hall – 7:00 PM

Keene: 1^st Saturday of each month at Keene State College, Bldg. 18, Keene, NH – 7:00 PM

Nashua:  Last Wednesday of each month at the Nashua public Library, Court St., Nashua, NH in the downstairs Theater Room – 7:00 PM

North Shore (MA):  3^rd Friday of each month, St. Paul Episcopal Church, Washington St., Peabody, MA – 7:30 PM

Boston Mineral Club:  1^st Tuesday of each month, Harvard University Geological Lecture Hall, 24 Oxford St., Cambridge, MA – 7:30 PM

Southeastern NH Mineral Club:  2^nd Wednesday of each month, St John’s Methodist Church, 28 Cataract Ave., Dover, NH – 7:00 PM