Diamond mining was once thought of as finding a pot of gold at the end of a rainbow. Common misconceptions were:
You can only extract diamonds from African mines.
There are no diamonds in North America.
You have to be a big mining company to find diamonds.
And the list goes on!
Knowledge and time have done away with all these misconceptions. Finding diamonds continues to get easier and easier.
Prospecting or mining for diamonds has been concentrated mainly in placer mining. Diamond bearing gravels (alluvial deposits) are concentrated in the Northwest Territories in Canada and the bulk of the U.S. The U.S.A. has the glaciers to thank for their good fortune. In the last ice age massive ice sheets pushed enormous mountains of gravel and rock into the U.S. and then melted leaving behind diamond rich deposits. These gravel and diamond deposits have, over time, become concentrated in rivers, streams and lakes.
It is interesting to note that early gold prospectors occasionally would get a diamond or two in their sluice boxes, usually trapped in the black sand, near the end of the chute. Not knowing what these little rocks were, they would toss them back into the stream as waste. Some miners thought the stones were quartz, not knowing what a rough diamond looked like. Since very few diamonds actually stick or get trapped in a regular sluice box, most miners rarely saw them though.
The best way for you to mine diamonds is in gravel in rivers and streams. This type of extraction is easiest because the stones (actually carbon crystals) are free or loose and can be panned or separated quite easily with the right equipment.
Types of mines
When it comes to diamonds, hard rock means blasting kimberlite volcanic rock. Diamond bearing kimberlite carries these stones to the surface through "pipes". The only way to free the stones is to blast and crush the ore for final separation.
Within the hard rock mining classification, there ar two main diamond mining methods:
This type of Hardrock diamond extraction technique is simply a top down mining approach. Typically a long spiral (corkscrew) open pit shaft follows the vertical kimberlite volcanic ore vein deep into the earth. There are practical limits on depth with this type of diamond mining.
Depending on the formation of the kimberlite shaft(s), a horizontal or sloping underground tunneling method will be employed. These shafts, also called a "decline" will be reinforced or supported by using a variety of bracing methods. Leaving pillars of standing rock or timber braces are some of the techniques used to hold up the rock roof as mining progresses.
Placer diamond mining, also called alluvial mining, involves sifting through sand and gravels to extract diamonds.
This method is common in Africa and used by most of the local people for diamond mining.
The number one reason placer mining is so common in Africa is that that Continent hasn't had glacial scouring of the diamond deposits. Kimberlite has decomposed and diamonds have been carried by rivers and streams into concentrations, both gravel (alluvial) and into clay, particularly blue clay, settlements.
Concentrations of Placer Diamonds
Like gold, diamonds have favored areas in which they concentrate. Many amateur prospectors ask the question "where are diamonds found?" Typically diamonds are located in higher numbers in rivers and streams.
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