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Exploration using magnetic and resisistivity and ip surveys (4 replies)
A good friend tells me... Well... Hmmm.... geophysics is used to identify areas that can be targeted for further exploration and, of themselves, say very little other than there is chargeable/magnetic material in some of the rocks. By itself it cannot be relied upon. That there are artisanal workings nearby gives increased confidence in what the geophysics has to say - something interesting is going on. It says nothing about grade, tonnage and often depth. Hence there is no "resource" or "reserve" in this project. There might be mineralization.
It is unclear from the report what the mineralization looks like. The photos were interesting but not revealing. Are the magnetic and IP anomalies from pyrite? magnetite? a combination? More needs to be known about the ore being mined nearby. Also you mention 8 m to bedrock yet suggests going to 60 m with a shaft or exploration holes. What happens at 60 meters that doesn't happen at 8 meters? It would be good to know.
I would suggest you put together a map showing with good precision (better than 1 meter accuracy) the location of current mining (where the ore is being extracted) and any survey data from the existing workings. It would also be good to get a sense of the grade being mined and the metallurgical properties of the gold bearing rock.
This depends upon getting the approval of the owners of those mines of course but with such a map and metallurgical information it would be much easier to decide on whether to put in a shaft or drill holes and where to put them to get the most information. It should not cost much money to get this information if the permission would be granted.
As to shaft versus drill holes, the issue in making the decision is one of risk. Having more data points reduces risk but you can't mine from the drill holes. If you puts in the shaft then the risk of getting the location of the ore wrong is increased but if the location is correct then production can start quickly. As Clint Eastwood would say, "How lucky do you feel?"
Hope that helps.
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There is no survey data from where the current miners are mining. In fact they never did any sort of survey, they did dowsing, using copper wire. People tend to do a lot of that here and surprisingly score. They don't care about any of these modern day surveys.
Trying to get their permission to do mags or ips on their property would be tricky. We are talking of people who are even concerned when they see you with a gps, there a belief among them that the gps finds gold and so you will be trying your luck on their gold. Its sad but funny at the same time. They do get a lot of gold but they could get more, much more.
On their property the mineralization is hosted in quartz veins. There is reasonable free gold hence their persistence with mining. I would need to do thin sections, met tests etc to have more details. I agree there is a lot that can be done but I have to draw the line somewhere as a small fish.
I understand there is no one method that can take me to the promised land but will need to do many more tests which are budget controlled. So at some point I will have to just dive in and see how I come out smelling.
I gotta summon Lady Luck and lock her up if I have to
I am starting a new gold mining project in Zimbabwe. I have contacted a Geologist and Geophysicist who did a Magnetic Survey on the target area. He also did a Resistivity and I.P. Survey. No other method was used and one has to dig 8 meters into mudstone to get to rocks of any kind as there are no out-crops. There are people mining near the area and his interpretations were also based on information he got from shafts dug by the other people nearby.
He tells me to be more sure it would be prudent to diamond-core-drill ten 60 meter holes along the target area which would cost US$48,000 at US$80/meter.
If I sink one 60-meter shaft in one of the positions identified by the surveys, it would cost me less than $20,000 to do so including buying the equipment and paying laborers.
As an artisanal miner would it not make sense for me just sink a shaft and hope, because generally, people mining within 200-meter radius of this area are getting very high yields of gold, more than 100g/ton sometimes? The hope would be the reef is basically the same as it is the same greenstone belt.
I have attached a report with pictures and diagrams that further explain the results. How much can I rely on the three methods of survey results?