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Coastal Digs through Old Mine Tailings for Copper, Gold

Processing the mine tailings could be an easy source of cash for the company since it appears that significant gold and copper were left behind. In this case the tailings are in ponds, which is probably why no one has endeavoured to reprocess them as of yet.

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TORONTO, ONTARIO–(Marketwired – Nov. 27, 2013) – COASTAL GOLD CORP. (TSX VENTURE:COD)(OTCQX:COGGF)(FRANKFURT:CY41) (the “Company”) reports that it has received assay results from the recently completed tailings vibracore drilling program at its 100% owned Hope Brook Gold Project in southwestern Newfoundland. Both tailings ponds 1 and 2 were tested with complete assay results shown in Table 1 and hole locations with results for gold shown in Figures 1 and 2.

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Before we begin, I’d like to point out that this Newfoundland company’s TSX ticker symbol is COD. If you’re not sure why that’s funny, you haven’t met a Newfoundlander.

Junior mining companies love snapping up old mine sites. They’re easy to market and have a proven track record of production. After all, it’s much easier to get investors excited about a past producer than an unknown, undeveloped land position. While one could argue that the upside is less interesting, there’s also a lower perceived risk in redeveloping a past-producer.

That’s not to say that reopening old mine sites don’t have inherent disadvantages. Old underground workings can be dangerous and difficult to navigate. The easy-to-access high grade ore is usually depleted. Old infrastructure can be costlier to clean-up than building anew. Environmental messes left behind by previous operators can be a serious liability. Still, the idea that a company will “reopen the mine” tends to get people excited.

Coastal Gold’s Hope Brook gold project is located on a the site of a gold mine that operated from 1987 to 1997. The deposit is hosted in Late Proterozoic (~575 million years old) volcanic and sedimentary rocks that have been structurally deformed and hydrothermally altered.

The deposit is fairly low grade and Coastal has set a cut-off grade of 0.5 g/t within the immediate area of the former mine workings (“constraining shell”) and 2.0 g/t outside the “shell” in defining their initial resource.

The company is currently working on defining a mineral resource estimate for the old mine tailings (waste rock). Old mines often used higher cut-off grades and tailings can sometimes hold significant grades of unprocessed ore.  It is not unheard of for companies or enterprising individuals to haul away old mine tailings for processing in order to make a few bucks.


Highlights include:

Tailings Pond 1 (all widths are true thickness)

  • 1.73 g Au/t* and 0.12% copper (Cu) over 2.39 metres (m) from Hole P8
  • 1.31 g Au/t and 0.18% Cu over 4.20m from Hole P13
  • 1.20 g Au/t and 0.15% Cu over 3.55m from Hole P6
  • 1.32 g Au/t and 0.13% Cu over 1.17m from Hole P3
  • 1.22 g Au/t and 0.08% Cu over 1.21m from Hole P18
  • 1.21 g Au/t and 0.06% Cu over 1.41m from Hole P28
  • 1.15 g Au/t and 0.13% Cu over 4.38m from Hole P10
  • 1.00 g Au/t and 0.18% Cu over 4.83m from Hole P9

Tailings Pond 2

  • 1.40 g Au/t and 0.08% Cu over 3.29m from Hole P47
  • 1.12 g Au/t and 0.08% Cu over 3.77m from Hole P52
  • 1.08 g Au/t and 0.05% Cu over 2.73m from Hole P56
  • 0.98 g Au/t and 0.11% Cu over 5.05m from Hole P64
* grams gold per tonne


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Processing the mine tailings could be an easy source of cash for the company since it appears that significant gold and copper were left behind. In this case the tailings are in ponds, which is probably why no one has endeavoured to reprocess them as of yet.


Dr. Bill Pearson, P.Geo., President & CEO of Coastal Gold commented: “These results have confirmed the results of the initial piston core sampling program in 2012 (see news releases dated March 29, 2012 and April 24, 2012) and indicate that the tailings contain wide spread gold and copper mineralization significantly above the historic reported tailings grade. We are moving forward with a NI 43-101 mineral resource estimate for the tailings based on these new drilling results.”

Allan Polk, P.Eng., Project Manager for the Hope Brook Preliminary Economic Assessment (PEA), said: “For the purposes of the PEA, we are now considering the existing tailings material as potential mill feed to either supplement the run of mine material or to provide stand-alone early feed for the project. Both of these options have the secondary benefit of allowing an optimization of the material storage balance for the project. Some metallurgical testwork has been done to investigate the potential of recovering metals from the tailings and more has been initiated as a result of these positive tailings assay results.”

As previously reported (see press release dated October 21, 2013) a total of 73 vibracore drill holes totalling 155 metres were completed on an approximate 100-metre square grid over the two tailings ponds, designed to evaluate the full thickness of the tailings and provide sufficient data to support a NI-43-101 compliant mineral resource estimate. Fifty-one of the 73 drill holes successfully sampled tailings with a thickness ranging from 0.3 to 6.0 metres and an average thickness of 3.0 metres. The remainder of the holes (22) encountered bedrock in areas where the tailings ponds where not filled. The previous shallow piston core sampling program indicated that the tailings contain an average grade of approximately 1.0 g Au/t (see news releases dated March 29, 2012 and April 24, 2012).

Drill holes from Tailings Pond 1 are generally higher grade. This is likely because most of the tailings in Pond 1 are reported to be from the earlier years of production when the historic mill lacked a copper flotation circuit for production of a copper concentrate hence had lower reported overall recovery. Most of the tailings in Pond 2 are reported to have been from the latter years of production when the plant recovery was higher due to the addition of the copper flotation circuit.

Tailings Pond 1

Tailings material with an average thickness of 3.12 metres was recovered from 25 of a total 29 vibracore drill holes at Tailings Pond 1. Assay results from the drill holes range from 0.57 g Au/t and 0.08 % Cu over a true thickness of 3.84 metres (hole P21) up to 1.73 g Au/t and 0.12% Cu over a true thickness of 2.39 metres (hole P8).

Tailings Pond 2

Tailings material with an average thickness of 2.94 metres was recovered from 26 of a total 44 vibracore drill holes at Tailings Pond 2. Assay results from the drill holes range from 0.44 g Au/t and 0.12% Cu over a true thickness of 3.33 metres (hole P73) up to 1.40 g Au/t and 0.08% Cu over a true thickness of 3.29 metres (hole P47). Drilling confirmed that the eastern half of this tailings pond has essentially no tailings.

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Since the tailing consist of consolidated (loose) rock, the vibracore drill is used to retrieve representative results from within the tailings. Vibracore is exactly what is sounds like: A 4-inch vibrating tube designed to shake its way into and retrieve samples from loose sediment.


Table 1: Summary of Assay Results for Vibracore Drilling Program, Hope Brook
Drill hole Easting Northing Au g/t Cu % Width (m)
Tailings Pond 1
P1 418615 5286965 0.77 0.10% 3.42
P2 418671 5286949 0.78 0.10% 4.19
P3 418815 5286739 1.32 0.13% 1.17
P4 418859 5286672 1.04 0.12% 2.23
P5 418894 5286593 0.61 0.10% 3.93
P6 418602 5286872 1.20 0.15% 3.55
P7 418657 5286787 0.73 0.17% 4.18
P8 418769 5286625 1.73 0.12% 2.39
P9 418541 5286786 1.00 0.18% 4.83
P10 418589 5286707 1.15 0.13% 4.38
P11 418657 5286621 0.97 0.14% 3.25
P12 418711 5286534 0.75 0.08% 0.66
P13 418765 5286457 1.31 0.18% 4.20
P14 418501 5286654 0.99 0.18% 3.07
P15 418559 5286574 0.71 0.08% 0.92
P16 418616 5286492 no sample*
P17 418676 5286414 0.93 0.09% 3.76
P18 418446 5286552 1.22 0.08% 1.21
P19 418501 5286479 no sample*
P20 418562 5286403 0.79 0.08% 1.33
P21 418615 5286320 0.57 0.08% 3.84
P22 418391 5286465 1.28 0.07% 1.81
P23 418451 5286381 no sample*
P24 418505 5286304 0.81 0.06% 5.14
P25 418337 5286411 no sample*
P26 418431 5286302 0.85 0.07% 5.97
P27 418431 5286235 0.57 0.09% 2.31
P28 418269 5286342 1.21 0.06% 1.41
P29 418331 5286287 0.65 0.08% 4.87
Tailings Pond 2
P30 419951 5285410 no sample*
P31 419778 5285520 no sample*
P32 419844 5285438 no sample*
P33 419661 5285530 no sample*
P34 419710 5285449 no sample*
P35 419464 5285601 no sample*
P36 419538 5285532 no sample*
P37 419585 5285457 no sample*
P38 419450 5285475 no sample*
P39 419494 5285421 0.80 0.14% 0.56
P40 419552 5285339 no sample*
P41 419392 5285542 no sample*
P42 419248 5285541 0.97 0.07%` 1.90
P43 419329 5285487 no sample*
P44 419386 5285406 no sample*
P45 419443 5285320 no sample*
P46 419499 5285237 no sample*
P47 419172 5285572 1.40 0.08% 3.29
P48 419161 5285491 0.77 0.08% 4.53
P49 419252 5285419 0.76 0.09% 0.62
P50 419368 5285249 no sample*
P51 419424 5285173 no sample*
P52 419116 5285430 1.12 0.08% 3.77
P53 419190 5285333 0.63 0.09% 3.40
P54 419304 5285174 0.63 0.07% 1.61
P55 419350 5285118 0.49 0.10% 3.26
P56 419067 5285347 1.08 0.05% 2.73
P57 419126 5285246 0.68 0.06% 4.60
P58 419186 5285166 0.64 0.09% 1.28
P59 419245 5285081 0.62 0.07% 3.81
P60 419301 5285000 0.64 0.08% 2.70
P61 418995 5285266 0.81 0.04% 3.40
P62 419049 5285182 0.92 0.06% 1.09
P63 419110 5285101 0.81 0.04% 2.26
P64 419166 5285018 0.98 0.11% 5.05
P65 419226 5284940 no sample*
P66 419012 5285067 0.67 0.05% 3.60
P67 419072 5284984 0.61 0.04% 2.87
P68 419128 5284925 0.54 0.13% 3.12
P69 419187 5284821 0.69 0.08% 3.61
P70 418958 5285001 0.61 0.05% 3.34
P71 419035 5284896 0.71 0.08% 1.50
P72 419108 5284829 0.69 0.09% 5.32
P73 419168 5284732 0.44 0.12% 3.33
Au = gold; Cu = copper; Width = true thickness; g/t = grams per tonne; %percent
*no sample. Hole for which “no sample” is reported were drill locations where no or very little tailings were present and no sample could be recovered.


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It looks like the second pond doesn’t have much to offer, and the company has said as much. However, it still may have some recoverable ore and dredging or draining the two ponds may ultimately be necessary anyway.



Coastal Gold is a Canadian mineral exploration company listed on the TSX Venture Exchange under the symbol “COD”. Coastal Gold’s flag ship property is the Hope Brook Gold Project located in southwestern Newfoundland, which has 12.4 million tonnes at 1.48 g Au/t for 590,000 ounces of indicated mineral resources and 8.2 million tonnes at 2.07 g Au/t for 548,000 ounces of inferred mineral resources (see technical report entitled “Updated Mineral Resource Estimate Technical Report, Hope Brook Gold Project, Newfoundland and Labrador, Canada”, effective October 1, 2012). Coastal Gold is currently completing an updated mineral resource estimate which will form the basis for a Preliminary Economic Assessment (PEA) which is also in progress.


The vibracore drilling program is a low impact coring method that allows for recovery of unconsolidated sediments using a four inch diameter aluminum core tube. The tailings core were logged, photographed and then split in half with one-half sent to the laboratory for analysis and the other half retained and stored on site. All core samples were prepared and assayed at ALS Minerals, with sample preparation done in Sudbury and analytical work done in North Vancouver. All locations of ALS Minerals are ISO 9001:2000 certified. The entire sample received was dried, weighed and crushed to = 70% passing 1mm. A sample split of up to 1000g is then pulverized to = 85% passing 75 microns (200 mesh) to produce a homogenized sample. A 50g aliquot is used for fire assaying with an atomic absorption (AA) finish to determine gold concentration. Copper was analyzed using a four acid digestion ICP (inductively coupled plasma-atomic emission spectrometry) method. Internal quality control includes the use of blanks, duplicates and standards in every batch of samples. The Company also conducts internal check assaying using certified external reference standards and blanks. Regular external check assays are performed at a second certified Canadian commercial laboratory. Coastal Gold also inserts external reference standards as a further external check.

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QA/QC can be a little difficult when dealing with old tailings. Often a team will be sent to pick through a rock pile “at random”,  but random can be a little tricky. The eye is always drawn to the more interesting rocks and depending on the size, a random sample does not always translate into representative sample. In this case it is a little easier since the company is drilling into the tailings, but dividing the samples into representative halves for assay still requires some objectivity.



Dr. John Gale, P.Eng., President of Fracflow Consultants Inc., supervised the vibracore drilling program. Dr. Gale is an independent qualified person as defined by NI 43-101. David Copeland, P.Geo., Chief Geologist, and Dr. Bill Pearson, P.Geo., President & CEO of Coastal Gold, both qualified persons as defined by NI 43-101, have reviewed and approved the scientific and technical content of this news release.

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