LOGGING AND SAMPLING PROTOCOL

Transcription

1 LOGGING AND SAMPLING PROTOCOL The following discussion will address a number of issues including; the physical taking of the samples, geological descriptions, sample numbering and handling, and the dispatch of the samples to the laboratories. All sample data as well as the photographs will be entered onto the appropriate database by the responsible geologist and checked by the supervising geologist on a daily basis. Three types of samples will be collected during the exploration programmes: Geochemical Samples samples will be assayed for its chemical elements. These may include manual sampling of pits, trenches and adits as well as RC drill samples. Drill Core Samples drill cores will be logged primarily for geological structure and then submitted for element analysis. Bulk Samples large volume samples for metallurgical testing Sample handling procedures, dispatch and sample storage guidelines are detailed below. 1. GEOCHEMICAL SAMPLES 1.1 Geochemical Samples Depending on the density of sampling required, the Project Geologist, in consultation with the Company Exploration Manager and the QP, will sample all shallow drill holes. Holes will be drilled down to bedrock where possible or to a depth of 5.0m. Individual holes must be marked with a plastic sample tag tied to a stake, clearly indicating the hole number using a permanent marker pen. Profiling Procedure: GPS surface collar in 3D, leaving GPS on, enabling GPS to increase the accuracy in measurement (Averaging). Record the date Measure total depth of hole, Geological rock type description Alteration recorded With the auger drill, spread a canvas/plastic sheet around the auger hole. After each meter drilled, the auger is taken out of the hole and but all the drilled material is collected in a sample bag (approximately 5kg) and the sheet is cleaned/ swept clean. Samples are clearly marked by writing the drill hole number and the sample number on the outside of the bag as well on a sample tag that is tied to the bag. Bags are to be sealed tight and transported back to the camp area. All samples are split using a riffle sample splitter. One sample goes to the laboratory and the other is kept on site as a reference. Samples to be bagged in strong plastic bags. One sample tag placed on the inside of the bag and one to the outside. Plastic bag ties and plastic tags to be marked with a permanent marker. 1.2 Trench and Pit Samples

2 Trench samples essentially represent an opportunity to test for variance in quality on the same horizon over a horizontal distance or of the change in lithology over the length of the trench. The following methodology is recommended: GPS surface collar at each end in 3D, leaving GPS on enabling GPS to increase the accuracy in measurement (Averaging). Clean one long face with a spade from top to bottom if the side of the trench or rock outcrop is to be sampled. Alternatively clean the bottom of the trench of any material falling from surface. Measure total length and depth of trench, Log the trench in as much detail as possible, noting alteration, structural features etc. on the log sheet Record the date Using spray paint, measure and mark intervals of 1m from across the base of the trench. Photograph the face/trench. Number the samples from any end, consistent with other trenches. Using a diamond saw in hard rock, or a small spade or geo-pick in weathered material to cut a V-shaped channel while collecting the material into a sample bag. Samples of approximately 5 kg should be collected. Where a visual change in alteration is observed, sampling lengths should be adjusted to reflect such changes at the discretion of the geologist. Such changes must be recorded by the geologist on the sample bag and on the log sheet RC Drill Samples RC drill samples will be collected by the drill crew at 1m intervals into a 20kg numbered bag and delivered to the sample preparation area at the camp. Field geologists should regularly observe the sampling to ensure that samples are taken according to the specifications in the drill contract. RC drilling should be carried out by experienced drillers using the appropriate equipment. This equipment would include compressors with sufficient air capacity for the depths and material drilled. Air capacity can be easily boosted by using auxiliary compressors that are capable of providing sufficient air to prevent water inflow below the water table. A downhole face sampling hammer should be used, and the use of stabilisers to prevent deflection of the hole near the collar is recommended. In addition, the hole should be sealed to prevent air and dust loss at the collar. It is good practice to implement the use of 'blow-backs' at the end of each sample run whereby the bit is pulled back from the bottom of the hole and the hole is cleaned out for a few seconds with air. RC logging is more difficult and does not give as much detailed information as diamond core. The depth of the water table should also be noted to assist with subsequent hydrological studies, and the weight of each sample should be measured in order to estimate the recoveries obtained (per cent recovery is calculated from the theoretical mass which should be recovered for that hole diameter). RC rod changes should also be noted in the logs, as well as the depths at which the hole was stopped for any reason. The penetration rate should also be noted to provide a relative measure of rock hardness. RC sampling should always be carried out with care so that the results can be successfully matched with any diamond twin holes and thereby allay any concerns regarding RC drilling as a resource definition tool. There is much debate regarding the sampling of wet RC holes,

3 and it is my experience that if the sample cannot be kept dry by the air pressure used, then the samples should not be collected at all. In other words, wet RC sampling is not acceptable. RC samples should be collected through a properly designed and fitted cyclone that minimises dust loss. After collection and weighing of the entire sample, a riffle splitter should be used to split the sample down to a manageable size for assaying, generally approximately 5kg. Spear sampling is acceptable if it is carried out properly and with due care in terms of sample homogenisation. Sample residues should be clearly marked and stored securely under cover. RC Cyclone Output (1 metre = kg) Chip Tray (for visual record) 25mm Split Logging 15mm Split Residue bagged and stored at field camp 15mm Split Oxide material >7 kg Sulphide material > 15 kg Sample for Laboratory (1.5 4 kg) Duplicate (back up) kg (bagged and stored undercover at field camp) Fractional samples taken (optional)

4 2. DRILL CORE SAMPLES Drill cores will be packed into metal core boxes according to the drill contract. The responsible geologist and/or geological assistant will: witness and verify the measuring of the depth of the hole, observe the correct packing of the core Observe the correct numbering the depth blocks, core losses/gains Ensure that the core is transported to the core yard with the minimum of disturbance Log the core according to the agreed format, recording the data on the provided log sheet and will include geological, structural and geotechnical parameters. Samples will be marked at 20cm intervals from the top with a red wax pen. Samples will be cut along the length, showing the maximum geological and structural features All core will be photographed and photographs forwarded to the core shed on a regular basis One half of the core over the target mineralisation will be sampled and the remaining half will be stored for future reference. Should a request for a duplicate sample be received, the stored half of the core will be quartered and the remaining quarter will again be stored. Capture the data onto the computer database on a daily base. A permanent core yard geologist will be responsible for the sawing, sampling and storing of the core. The responsibility of the field geologist is the marking and logging of the core. 3. GEOLOGICAL LOGGING For diamond drillholes, the range of data shown is generally length of coring run, in metres and millimetres, as defined by the driller s core blocks; length drilled; measured length of core recovered (in metres and millimetres); and calculated per cent core recovered; a list of assays; a graphic lithological section; lithology degree of weathering, colour, grain size, field rock name (often in capitals or underlined), proportions of rock minerals, attitude of bedding or foliation (the angle between the planar structure and the long axis is generally stated, often termed θ), attitude and spacing of joints; and attitude, width and description of sheared zones. The interval in which ore minerals are present is listed separately, with ore mineral species in capitals or underlined, and with notes on weathering, grain size, grain relationships, orientation of ore minerals and of zones of mineralisation, gangue minerals present, their grain size and relation to the ore minerals, and a visual estimate of grade in per cent metal. Diamond core should be logged in as much detail as possible while maintaining a coding system that is not too complex. It is often a good idea to use summary logs for modelling purposes and to keep the detailed logs for later reference if required. Diamond core should also be geotechnical logged and photographed wet. Core recoveries should be routinely determined for all drill runs. It is good practice to carry out geotechnical logging, determine core recoveries and even to photograph the core when it is still in the split tube prior to transferring to a core tray. If this is not possible, all man-made breaks should be clearly marked. Core boxes should be transported to the base on a daily basis and stored under cover. All core should be logged within 2 days of completion of the hole. Due to high humidity and rainfall, core left exposed will be weathered very fast. All observations are to be recorded on

5 the company logging sheet and the data transferred to the database at least on a weekly basis. A logging procedure is described below: Lay the complete core out in the core boxes Identify and record major lithological changes and lithological / formation boundaries Record major structural features such as faults, etc. Record sedimentological features such as upward fining units, scour surfaces and unconformities Log core in recognisable units such as massive banded iron stone unit, massive sandstone/quartzite unit or upward fining cycle or appropriate unit for igneous or metamorphic rocks Record; o Rock type o Degree of weathering and depth of weathering o Colour o Grain size o Rounding o Texture o Banding and thickness o Bedding structures o Basal contact type o Sedimentological environment o Identifiable minerals and percentage of major minerals All geological logging to be performed by the field geologists and the sampling by the core yard geologist after the logging has been completed. Diamond core should be joined and aligned prior to marking off with a centre line for cutting with a diamond saw. Core should generally be sampled on a geological basis with a predetermined maximum sample interval. In order to estimate the sampling error in the assays and to monitor the performance of the laboratories used for sample analysis, field duplicates, standard reference samples and blanks should be sequentially added to the sample batches and the results stored in a separate quality control database. This will facilitate the extraction, analysis and monitoring of the results, and allow the analytical precision and accuracy to be quantified. Each of these quality control samples should be inserted into sample batches at a frequency of 5% or 1 in 20. Field duplicates can be collected during surface sampling by taking a second sample adjacent to the original (not for coal). RC field duplicates can be created by taking a second split of the same sample interval. Field duplicates of diamond core are more problematic, and can only really be collected by using the other half of the core or by quartering the core. We have often elected to request the sample preparation facility to create two splits of the same sample after jaw crushing the entire half core interval prior to final milling. Although this is not a true field duplicate, these samples will give an indication of sampling error and minimise the impact of the error associated with sample preparation. Standard reference samples are available commercially. Whilst laboratory personnel will know that the samples are standards, the use of a wide variety of standards should ensure that the expected grades will not be predicted. Alternatively, the standards can be inserted into the sample batches in the laboratory after the final stages of sample preparation. This is often not practical, but has the advantage of requiring less standard material and preventing the laboratory personnel from knowing which of the pulps are standard samples. In this scenario, the standard samples are substituted for the original samples, which are 'dummy' samples made up from old RC bulk reject samples. This process requires close monitoring and supervision, but is very effective. The use of pre-prepared standard reference samples is also useful in determining sample preparation error.

6 Blank samples can be obtained from any source of rock that is known to be barren, such as local granite outcrops, aggregate or river sands. An alternative if these are not available is to use old RC bulk reject samples that previously assayed at below detection. 4. Drill hole and Sample Numbering It is recommended that a consistent numbering system be developed that adequately identifies the project, sampling method (surface grab, trench, drill core or RC) followed by a number in sequence. This must be recorded together with date sampled and the coordinates, including the collar elevation. 5. SAMPLE PREPARATION AND DISPATCH All samples will be stored under cover on raised platforms to prevent degrading of the plastic bags. Core trays will be stacked in piles no more than 1.5m in height and in a numbered sequence. Samples from the different resource blocks should not be mixed and a mechanical barrier constructed to ensure that the samples are not mixed When RC drilling, surface and pit samples arrive at the core yard, they will be lined up in sequence and checked that the depths match from one bag to the next and also match the sample log sheet. Errors should be corrected by the responsible field geologist and is not the responsibility of the core yard geologist Each sample will be weighed. Using the riffle splitter, sample weight will be reduced to between 1kg and 5kg for all samples, excluding drill core samples. Surface or pit rock samples should be broken by hammer and care taken to take a representative sample, not to only pick the best looking mineralisation for assays. Drill core samples, starting 50cm above the mineralised area and ending 50cm below the mineralization, will be split with a diamond saw and then sampled, the whole half-core to be enclosed in the bag. RC drilling and pit samples are numbered in sequence from the top to the total depth with the numbering correlating to the drill depth. For coal samples, only the coal interval and all inclusions are sampled not the hanging wall or footwall. Where the inclusions (sandstone and shale are more than 50cm in length, they must be sampled separately. For thicker units, samples of 1m will be taken, starting from the bottom contact. If the upper sample is less than 50cm, it can be included in the sample below, if it is more than 50cm, it will be sampled separately. In the case of multiple seams, sampling and sample numbering will start at the lowest (deepest) seam. For base metals, sample intervals are reduced to 20cm and should continue into the hanging wall and footwall for 1m at the same 20cm intervals. Hanging wall and footwall is defined as the point where visible mineralisation ends. Sample bags to be marked with all the relevant sample data by permanent marker. The sample will be double-bagged with a sample tag inside the sample and a second tag between the two sample bags. Sample bags to be closed with a plastic bag tie, and packed into containers, the weight of a container not to exceed 50kg. Samples are recorded on a sample dispatch sheet, one sheet filed; one sheet is enclosed in the box in a sealed plastic envelope. Sample dispatch is to be recorded on the sample sheet that should be recorded on the computer by this time and stored in the database. Boxes are to be dispatched to the approved laboratory on a regular basis.

7 On receipt of the assay results, the results should be entered into the database onto the relevant sample sheet. The remaining sample material will be double bagged and stored in numeric sequence in the core and sample storage area under cover and core trays in core racks.