"Nature's Fireworks" - A Beginner's Guide to OPAL - Part 2 World Deposits

Written by Stuart Bazga

Althoughrepparttar largest opal fields are in Australia, opal is also found throughoutrepparttar 145288 world from Europe torepparttar 145289 South Americas, North America and South East Asia. It has been mined in Brazil, Honduras, Indonesia, Mexico, Hungary, western parts ofrepparttar 145290 USA and more recently Canada.

Following is a synopsis ofrepparttar 145291 countries where opal is currently mined:


The Mexican opal fields are primarily located inrepparttar 145292 Queretare and Jalica regions. These regions have been known to be producing opal sincerepparttar 145293 time ofrepparttar 145294 Aztecs, andrepparttar 145295 opal is commonly referred to as “Fire Opal.” The colouration ofrepparttar 145296 Mexican opal ranges from bright red to orange and arerepparttar 145297 only ones faceted rather than left as cabochons.


Since 1973 opal has been mined in British Colombia, with gem quality opal being discovered atrepparttar 145298 Klinker, Queen and Eagle Creek mines inrepparttar 145299 1990’s. Precious opal from Klinker is found to have excellent brightness and multicolour flash. Bothrepparttar 145300 Queen and Eagle Creek mines contain occurrences of transparent, translucent or opaque deposits of common opal.

United States of America:


Opal mining isrepparttar 145301 second largest contribution torepparttar 145302 total out put of gem production inrepparttar 145303 state. Varieties of opal being mined include precious, which comes in a varity of colours (white and pink, yellow, blue and pink) as well as common opal.

"Nature's Fireworks" - A Beginner's Guide to OPAL - Part 4 Mining , Cutting and Caring for your opal

Written by Stuart Bazga

Individuals rather than large mining companies do mining inrepparttar Australian opal fields. The reason for this is that opal is particularly elusive; it is not found in great amounts at a particular level or in a particular area, but is found at varying depths beneathrepparttar 145287 surface and is usually found at levels up to 25 metres deep.

Although in reality all that is needed to get started mining opal is a pick, most miners now consider a jackhammer and an electric hoist – a machine used to get opal-bearing dirt torepparttar 145288 surface –repparttar 145289 minimum equipment needed. Most shafts are now drilled using a drilling rig. After a shaft has been sunk andrepparttar 145290 opal level identified, horizontal drives are dug.

After bringingrepparttar 145291 dirt torepparttar 145292 surface, it is initially processed by washing away allrepparttar 145293 ordinary dirt and leaving behind potential opal stones. This is usually done in an “agitator,” a modified stationary cement mixer. Water is pumped through whilerepparttar 145294 dirt rotates inside. Sludge pours fromrepparttar 145295 mesh-covered openings inrepparttar 145296 side ofrepparttar 145297 agitator asrepparttar 145298 dirt is washed away. What remains are known as tailings.

This final process is eitherrepparttar 145299 most exciting or disappointing part ofrepparttar 145300 hard work of opal mining. It is at this point that it becomes apparent how much, if any, opal there is among allrepparttar 145301 dirt that has been mined.

Sinking a Shaft:

This is one ofrepparttar 145302 most effective ways of finding opal, but alsorepparttar 145303 most laborious. The length ofrepparttar 145304 shaft can be as short as three meters or as long as twenty.

A variety of tools are needed, including a hand windlass or motorised winch that is placed overrepparttar 145305 hole, liftingrepparttar 145306 dirt torepparttar 145307 surface. Some miners will use an expensive vacuum-cleaner apparatus called a “blower.”

Oncerepparttar 145308 bottom ofrepparttar 145309 shaft has been reached (whererepparttar 145310 opal-bearing dirt begins),repparttar 145311 miner begins gouging away very slowly. A horizontal tunnel is dug inrepparttar 145312 hope of finding a seam of precious opal or scattered “nobbies.”

Puddling and Rumbling:

This technique is used oncerepparttar 145313 opal dirt has been transported away fromrepparttar 145314 surface, usually by trucks. The dirt is first placed in a large mesh-lined drum. Water is pumped through it as it rotates, turningrepparttar 145315 dirt into sludge.

The sludge escapes throughrepparttar 145316 mesh inrepparttar 145317 sides, leaving only pieces of rocks, and hopefully opal.

Open-cut Mining:

Open-cut mining is created by running over a large area of ground with a bulldozer, slicing awayrepparttar 145318 dirt untilrepparttar 145319 opal level is reached. Although this method is very expensive,repparttar 145320 chances of finding opal are increased as a larger area can be mined at once.

Noodling: Noodling is when a person goes over what other miners have rejected as rubbish. All that is needed by a “noodler” is a sieve and a very keen eye.


Unprocessed opal straight fromrepparttar 145321 ground is known as “rough.” The miner may sell it at this stage, or he may choose to continuerepparttar 145322 processing himself. Althoughrepparttar 145323 potential value ofrepparttar 145324 opal can be estimated whilerepparttar 145325 material is unprocessed, its actual value cannot be established at this stage. The rough opal, although it may look as if it will cut well to produce valuable stones, may have faults within it. Conversely, an ordinary looking piece of rough may produce a magnificent gem. The choice of selling “inrepparttar 145326 rough” or continuing processing belongs torepparttar 145327 miner.

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