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Saturday, May 21, 2016

San Ramon - saint or sinner?

We’re been reading some great press releases from Impact silver (IPT.V) about the thick intercepts from the drilling below the San Ramon Deeps Mine levels.
  •  May 05, 2016 PR (link)
  •  March 02, 2016 PR (link)

The press releases give us a table of the results, but don’t provide a map/section showing where the holes intercepted mineralisation, all we get is:

“To date this deep vein has been exposed in mine workings on Levels 16.5, 18, 19, 20 and 21 over a length of 180 meters where mining has encountered true widths of two to seventeen meters. The drill holes in this news release outlined the vein to a vertical distance of 25 to 75 meters below the current mine workings. (For a section of the San Ramon Deeps Zone and drill holes, see the San Ramon Mine slide in the PowerPoint Presentation on the company website at

And here is the slide in question, can you see where the holes are located?

San Ramon Long section from Impact presentation

 OK, that isn’t very clear, so let’s zoom in a bit

Which drill-hole is which? Note the tightly spaced drilling (25m x 50m or less)
Ahh, that is as clear as mud, it is still hard to see which drill-hole is which, but I’ve created an improved version.

Red = May PR intercepts; Blue = March PR intercepts. I've also added a scale bar
 Why don’t we do a quick back of the envelope calculation for the amount of mineralised material this drilling has defined?
  • The drilling has defined a 60m x 50m zone with mineralisation
  • We'll add 20m to horizontal extends and 25m down dip giving us a block that is 100m x 75m
  • Average width (arithmetic mean) of the structure is 11.35m
  • I'm using a specific gravity of 2.8 tonnes/cubic meter
  • (100 x 75 x 11.35) x 2.8 = 238,350 tonnes of mineralized material.
    • equivalent to 3.6 years of at current production levels (66,000 tonnes for 2015)
That is an excellent result, but when we start to dig a bit deeper and pull apart the assay results, what will we see?

San Ramon - PR drill intercepts - i.e. the widest zones reported in the PRs

 We see that there is a zone of thick (>10m) medium grade (>250 g/t Ag) mineralisation below the San Ramon Deeps Mine.

What will happen when we split out the narrower, high grade intervals?

San Ramon - split assays showing high grade and residual grades from drilling
 It can clearly be see that the San Ramon structure consists of a high grade, reasonable width footwall and handing wall veins surrounded by a variable mineralised halo, but on average the veins appear to grade between 250-500 g/t Ag over widths of approximately 2-4m.

The drill-hole data appears to show a plunge in the ore-shoot (red arrow) where the structure appear to be getting thicker and with high grades, and it will be interesting to see what intercepts come from this area, they should be good.
What is interesting is that in earlier press releases referring to the San Ramon drilling, they refer to more than one vein (a series of hanging wall veins).

San Ramon logged veins

Isometric view of split assays - we can see that there are narrow high grade zones surrounded by lower grades
 Are we seeing something like this?
Cross section through San Ramon - are there 2 veins that join at depth leading to thicker, higher grade mineralisation?
Let's go back to our back of the envelope calculations, and focus on the intercepts that are >200 g/t Ag, and use historic results (from 2015), to see how our mineralized zone changes.
  • Drilling has defined a zone that is 100m x 65m
  • Mean widths of >200 g/t intercepts is 6.3m
  • SG of 2.8
  • (100 x 65 x 6.3) x 2.8 = ~115,000
This is still an excellent result, and that is nearly 2 years of additional resources, and drill-hole 205 looks very interesting, as there has been limited drilling around this zone, but there are good  indications that Impact can expand this zone into a reasonable amount of good grade (>250 g/t Ag) mineralisation that they can mine in the future.

It will also be interesting to see if they try and access this zone earlier than planned so that they can mine the high grade material as soon as possible.

During these difficult times, it is important that companies present information clearly. Why couldn't a company like Impact spend a bit more time and effort to present the drill-hole data with some nice plans and sections so that their shareholders could fully appreciate the hard work that Impact's exploration team have put into drilling these holes.
Drill-hole 205 appears to have intersected an strongly mineralized structure, that could provide a relatively large amount of mineralisation that is significantly higher grade that was has been mined recently (193 g/t Ag in 2015 and 159 g/t Ag in 2014), that could provide some highly profitable ore for the Zacualpan mill.

I think Steve's (Jobs) quote sums it up for me: “You've baked a really lovely cake, but then you've used dog shit for frosting.”

Here is the link to the Leapfrog Viewer file so you can see what I’ve done. As I didn’t have any collar information, I made the following assumptions:

  • The San Ramon vein is vertical
  • Hole dips were calcuated from the true vs core lengths (I've found a use for trigonometry!)
  • I recalculated the intercept depths bu assuming that plane of the section corresponded to the 1st intercept in each drill-hole.  I later modified several holes to make sure that the Immaculada veins all lined up.
  • The coordinates in the file are not real world coordinates, but I've used the bottom left corner of the section as 0,0.
Thank you


  1. Another superior example of advanced rock dog guruism for dum dums. Take a bow. We've profiled this baby ...