I told u guys (for those who follow the blog, and for those who really knows me in real-life) I love volcanoes. and now I'm sooo into gemstones. Volcanoes + gemstones are like mother and daughter, do u know? well at least for most of em.
Here are some research i did... (different paragraphs are taken from a different sources)Gemstones are a product of the earth. Some, like diamond and zircon, were formed deep in the earth and brought to the surface by explosions (volcanic) of molten rock . Many, like topaz, tourmaline and aquamarine, crystallised slowly from hot fluids and gases as they cooled and solidified, far below the surface of the earth. Others formed from liquids filtered into cracks and pockets in rock, like Australian opal. Some, like garnet and jade, formed when rocks were heated and pressurised by earth movements, and recombined to form new, different minerals.
Most diamonds are derived from volcanic rocks called kimberlite (named after the famous South African town of Kimberley where these rocks were first described) and lamproite (the host rock for the Argyle diamond mine in Western Australia ) which occur as vertical pipe-like bodies called diatremes. Kimberlite forms from a very explosive volatile-rich magma that forms deep down within the Earth (greater than 150 km) and rises rapidly to the surface because of the high fluid pressure. As it rises, it fractures the surrounding rock explosively and so, most kimberlite pipes contain abundant xenoliths from all levels of the mantle and crust that the kimberlite has passed through on its way to the surface. Kimberlites most commonly occur on the old continental cratonic regions of the Earth though themselves range widely in age from thousands of millions to tens of millions of years.
The best-developed tourmaline crystals are found in pegmatites and metamorphosed limestones in contact with granitic magmas, as well as certain sedimentary deposits. Gem-quality pegmatites are found in the United States (Southern California, Connecticut and Maine), Brazil, Elba, Madagascar and the Ural Mountains.
Sapphires are the colourless, yellow, green, pink and blue gem-quality varieties of the mineral corundum. They formed deep in the Earth's crust and were brought to the Earth's surface in basaltic magmas as xenocrysts. However, they only occur sporadically in the basalts and are uneconomic in these rocks. Economic sapphire deposits are only found when the basalt is weathered and eroded away, leaving behind the heavier minerals such as sapphires and zircons which become concentrated in placer deposits.
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resources ::
- Australian Museum Online
- Desert USA
- Ametyst Galleries
- book :: The Book of Stone
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