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batalhadematos

Alluvial Diamond Deposits

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Hi all,

I need your help on identify alluvial diamond deposits using remote sensing.

Does anyone have knowledge on this topic?

Some of the question I have:

- What minerals should I look for when the target is alluvial diamonds deposits (kimberlite could also be a target)?

- Can anyone guide me on the steps required for identify those on a Landsat-8 scene?

Thank you very much

Regards

Paulo

Edited by batalhadematos

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Hi Paolo

Are you asking (or your employer) miracles from remote sensing, and especially with free resources, like LandSat. Have you check the cloud coverage in your target area ? 

You can identify only  favorable areas (alluvial fields like meanders, cone shapes, etc). At the Landsat resolution will be difficult.....

Then, quatre quatre pieds, meaning foots on the ground and sampling.

It is a long  process painful  lounge and expensive: collect around 200 l of alluvial,  concentrate by panning, then carefully observe the heavy  minerals associations. A lot of samples like this......

Observation there in the field and also in specialized and expensive laboratories (they are experts specialized in heavy minerals microscopy). I am sure you know  all these.....

You can have/or not diamonds, or kimberlite indicator minerals. Keep in mind that perhaps only one of ten kimberlites bodies is "pregnant" with diamonds  

Regards,

Iulian

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Hi lulian,

Not exactly a miracle to achieve god results if we target just the minerals and not the diamonds itself (based on several tesis we can found on Internet).  Unfortunetly I lack of knowledge on Geology/Geoscience for implementing such technics.

Yes, for locating diamonds, the process could be expensive (also time consuming as you state) but do not believe that's more expensive than the actual methods applied which requires more onsite intervention (aeromagnetic data collection for instance). Usually we use "artisanal miners", which is cheaper. We have a rule here... if there are "illegal artisanal miners" on the target area, there are diamonds there. That's why we mainlly target alluvial diamond sources (not the kimberlite itself). On this region, at least 1 out of 10 people is an illegal artisanal miner, or at least is supporting a small group of artisanal miners.

I don't realy need to accurately located those alluvial diamond sources (I know what's behind the process). What I really need is to locate areas where the minerals related to diamond are present (I don't even know what those minerals are for sure) and I do believe to be easier to locate, other than the diamonds itself and since our region is very rich on diamonds presence, that's a good chance to find diamonds on those areas.

"Keep in mind that perhaps only one of ten kimberlites bodies is "pregnant" with diamonds ...". Yes. I am care about this and also know that depending on the area where the targets are located, this relation increases. Just to have an idea, one of the biggest open sky mining in the world operating is located here  (I think it's the fourth) and when the project started, they found 17 kimberlites and gess what... all of them were "pregnant". The project is named Catoca.

Actually I am looking for remote sensing professionals that might be interested on the project I have.

Regards

Paulo

Edited by batalhadematos

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Hi Paolo,

Remember from my text: "collect around 200 l of alluvial,  concentrate by panning, then carefully observe the heavy  minerals associations".  

I saw some papers telling about 100 kg (the minimal I think). We were more conservative and prudent in some projects.

It is a large quantity; depending on on the pan size, at least 10- 20 pans to wash. Finally, depending on the area, you will obtain some hundreds of grams of heavy minerals; among them, a lot without  significance, like magnetite.

And then, in less quantitiespyrope and eclogitic garnet, chrome diopside, picroilmenite, chromite;  and, to a lesser extent, olivine . The indicators.

These are the indicators about a kimberlite  body. The kimberlite is decomposing fast and will leave this mineral traces in the alluvial, but diluted with other minerals, depending on the distance.  It is what you are searching. 

Personal (from some  sustained field experience, and also a lot of study for Remote Sensing or GIS)  I don't think that you can discriminate those minerals, in such small quantities, basis on remote sensing, in  alluvials.  To few, in order to have a significant spectral signature.  See an article, about the kimberlites*

As a good help, starting from the satellite data, you can do a geomorphological analysis. Discriminate well and precise the hydrographic network,  then to locate some favorable areas (terraces, dejection cones),  for heavy minerals concentration. Among them, beside the indicators, you can find, or not, diamonds (3.52 SG).  It is what I done,  in my projects. Not Angola, but nearby.

Then, to start exploring, as I wrote before, on the ground.  Or direct mining, with the risks of acquiring heavy equipment and be without enough reserves.

I don't know if you have an exclusive  license; if yes, can you send me the coordinates, in order to see what it is available (satellite) for that area ?

If you are prospecting, and the area is confidentially, please send something like an nearby area, one-two hundreds kilometers  distance.

They are some new satellite data and I want to see the confidence, if you are agreed.

Regards, 

Iulian

*    http://www.hgimaging.com/PDF/Kruse_IEEE2000_Kimberlites.pdf

"Higher spatial resolution data (1.6m AVIRIS and 4m HyMap acquired in 1998 and 1999, respectively) are being used to map additional detail. Poor exposures, vegetation cover, and weathering, however, make identification of characteristic kimberlite minerals difficult except where exposed by mining. "

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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I know by experience when i was visiting a project site in Western africa , if you see a black dude with an AK-47 near an alluvial areas, then that is where the Diamonds are. ;)

i hope that helps.

  • Haha 1

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5 hours ago, uriendemonav said:

I know by experience when i was visiting a project site in Western africa , if you see a black dude with an AK-47 near an alluvial areas, then that is where the Diamonds are. ;)

i hope that helps.

Usually they are more..... In happy cases, from the state...Otherwise, a militia.... 

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