Motherlodetv.net client Bayhorse Silver put out two news releases (here and here) on samples drawn from its Bayhorse Silver mine in Oregon. We sent Bayhorse CEO Graeme O’Neill a few questions on the releases and were fortunate enough to get quick answers.
ML: Your last two press releases reported assays from seven samples. Where in the mine were those samples taken? Were any taken in the old workings which you recently re-opened?
Bayhorse Silver/ Graeme O’Neill: All the samples were taken from locations in the far reaches of the mine at the east end of the recently reopened workings. This section, called the Big Dog Zone, is of historic importance as this was mined in the 1920’s and comprehensively sampled again in 1976. That formed the basis for the 1984 mining program. We were delighted that the first 7 samples assayed, including 73 oz/t and 54 oz/t, are comparable to the highest 1976 sample of 69 oz/t. Prior to that samples as high as 216 oz/t were taken. The recent assays show that the historic numbers are not a fairy tale, but are concrete evidence of the high to bonanza grades mined at the Bayhorse. Sampling, including long hole drilling sampling, is now being systematically done from the Big Dog in the east, for over 550 feet of strike, and 1,500 feet of raises, stopes and drifts, to the western end of the workings.
ML: You put out two news releases about the same samples. Why?
BHS: We assay for 35 elements as well as silver and gold. Sometimes we receive the full results at the same time, in which case we disclose them all together. This time the first results received were silver and gold. The grades were so high that we believed it necessary to disclose them immediately, as sometimes, as much as assays are kept under wraps, news leaks, and we wanted to avoid that occurrence. We received the base metal assays late Friday and wanted to put the silver/gold results in perspective with them without delay, which is why there were two releases.
ML: You indicated that the presence of base metals in the samples made your ore sorter work more effectively. Why is that and what sort of upgrade are you experiencing.
BHS: The ore-sorter is an extremely effective pre-processing tool for us in reducing waste material from mineralized material. This reduces energy costs. It uses Transmissive X-Rays coupled with extremely sophisticated computer software to differentiate between mineralized, and non-mineralized rock, and is particularly effective doing so with sulfides. I was highly trained in electronic theory and practise during my years in the Navy, so I probably have a better understanding of the technology used, what different X-Ray frequencies can do, and what results it can achieve, than most.
This effect can be seen when going through airport X-Ray scanners. If am unsure of a sample I am taking back with me, I look at the airport X-Ray image, that fortunately displays in color. The blacker the image is, the better the mineralization. Green, not so much. A highly effective visual check.
The differentiation between high grade and low grade can be affected by the type of mineral. As an example, tetrahedrite is one of our minerals and consists of copper-arsenic-antimony, and for simplicities sake, the silver inserts itself into that matrix.
Our mineralization is in what is called a stockwork, as can be seen in the photo we posted with the news release. This gives us veins of higher density silver bearing mineralization snaking though lower density rocks. The transmissive X-Rays are absorbed more by the sulfide mineralization than the lower density, non-mineralized rock and the computers can distinguish the different absorption rates and select or reject them accordingly.
For us, the last thing in the mix is making sure we get the primary crush right. We had originally selected plus 8mm to minus 25mm as our most effective crush size, but after all this work we have done we can probably reduce the top size to maybe 20mm to help increase the selectivity further.
ML: In the releases you mention the forthcoming 43-101 resource estimate. Will that estimate include the resources contained in the newly re-opened “old workings”? Will the increased effectiveness of the ore sorter be included?
BHS: We have been told the report is nearly finished, and yes, Apex have been to the furthest western extent in the newly accessed workings and taken samples, so it will include the mineralized zones there. Visually seeing the extent of the width and thickness of the zone is very important in understanding the extent of the Bayhorse mineralization.
All of the results we have achieved with the ore-sorter during these past eight months has been presented to the report preparers, so yes, the effectiveness will be part of the report.