Obsidian is of low significance as a material for gemstones, but the so-called volcanic glasses provide interest for the many uses to which they have been put by aboriginal man and by the enigma of their genesis. Obsidian is formed by the rapid cooling of volcanic lava which, had it been allowed to cool slowly,…
Rose quartz is one of the most pleasantly seductive varieties of quartz. The pink to rose red colour is caused by titanium and iron. Rose quartz is usually too cloudy or pale to be used as a cut gemstone, although a few exceptional pieces are found with enough clarity and colour to make fine gems.…
The violet and purple varieties of quartz provide the most prized and in many respects the most interesting of the large family of quartz minerals. Amethyst, the name by which this variety of quartz is known, is of ancient derivation. Pliny stated that the gem was so called from the colour being near to, but…
Tektites are still poorly understood. They are irregularly – and at times elaborately – shaped nodules and blobs of a glassy substance. They have no crystal structure and are therefore similar to obsidian, but are not associated with volcanic processes. Their chemistry is unique and unexplained. The leading theory concerning their origin is the “Meteorite…
Citrine is a variety of quartz, the colour being in the range from yellow to golden brown to burnt amber. Natural citrine (yellow quartz) is not common and occurs only sparingly in many large quartz deposits. As such it is greatly prized by crystal therapists and healers. Most of the yellow and brownish-yellow quartz, which…
