Ultraviolet lights contain mercury vapor. Although it is has many practical applications, mercury is extremely poisonous. Where mercury has polluted water in the form of water-soluble salts, it has entered the food chain. Over long periods, mercury contamination can cause permanent brain damage, as well as harming the liver and kidneys. At its finest, chrysoprase is a vibrant green and the most valuable of the chalcedonies.
Chrysoprase is the most valuable variety of chalcedony, a microcrystalline form of quartz.
Its apple green coloring is caused by the presence of nickel oxide in the quartz. Chrysoprase rates 8 out of a possible 10 on the Mohs scale of hardness, yet its color is delicate - fading when subjected to heat or sunlight. Many deposits of chrysoprase have now been completely worked out. The best quality specimens are now derived from deposits in Queensland, Australia. Chrysoprase cameo set in gold Crystal healers believe that chrysoprase can alleviate negative emotions like anger and depression, and promote positive mental qualities such as tolerance, kindness, and creativity.