TORONTO, ONTARIO--(Marketwire - Oct. 1, 2012) -Castillian Resources Corp. (TSX VENTURE:CT)(OTCQX:CTIIF) ("Castillian" or the "Company") is pleased to announce an update to its National Instrument 43-101 ("NI 43-101") Mineral Resource estimate for the Hope Brook Gold Project in southwestern Newfoundland which was previously released on February 14, 2012. This update incorporates results from the 4,549 metre, 15 hole, Phase I diamond drilling program. This drilling confirmed major pillars in the Mine Zone area, confirmed locations of underground workings in the former mine and further extended the Southwest Extension target zone (see press releases dated June 5, 2012 and June 25, 2012). The updated mineral resource estimate is presented in Table 1 below.
As shown in Table 2 below, total Indicated Mineral Resources increased 102% to 590,000 ounces of gold from the February 14, 2012 estimate. Total Inferred Mineral Resources had a modest decrease of 26% to 548,000 ounces of gold, which is the result of the successful conversion of Inferred to Indicated Mineral Resources through the 2012 diamond drilling program. Within the constraining shell, there was a significant increase in grade in both the Indicated and Inferred Mineral Resources, reflecting the confirmation of grade in pillars and location of underground workings.
Dr. Bill Pearson, P.Geo., President & CEO of Castillian, stated: "We are delighted with the results of this mineral resource update, which was accomplished with a limited, but highly targeted, drilling program. Our technical understanding of the deposit continues to grow and the mineral resources remain open along strike and downdip. Recent field work has outlined a promising target zone just 150 metres north of the Mine Zone. In addition, there is excellent potential to outline new zones along the more than eight kilometres of underexplored mineralized structure that has been identified to date." Dr. Pearson continued: "We have completed detailed planning for the next phase of diamond drilling and have two diamond drills already onsite."
The mineral resource estimates are presented in Table 3 below at different cut-off grades to demonstrate the sensitivity of the mineral resources to change in grade.
The updated mineral resource is based on 646 diamond drill holes totaling 129,264 metres of historic and recent drilling. This includes 105 surface diamond drill holes totaling 32,265 metres completed by Castillian from September 2010 to June 2012. Mineral Resources have been estimated within a constraining pit shell at a cut-off grade of 0.50 g Au/t and below this shell at a cut-off grade of 2.0 g Au/t. Details on the mineral resource estimation procedures are given in the notes below. An updated NI 43-101 Technical Report on Hope Brook outlining the procedures for estimation of the mineral resource estimates presented herein will be filed on SEDAR within 45 days of the date of this press release.
NOTES ON MINERAL RESOURCE ESTIMATION METHODOLOGY:
- Mineral resources are estimated in conformance with the CIM Mineral Resource definitions referred to in NI 43-101 Standards of Disclosure for Mineral Projects. Pierre Desautels, P.Eng., Principal Resource Geologist, and Jay Melnyk, P.Eng., Principal Mining Engineer, both of AGP Mining Consultants and Qualified Persons under NI 43-101 who are independent of the Company, have prepared and authorized the release of the mineral resource estimates presented herein. The Castillian and historical diamond drill hole databases and geological model developed by Castillian were reviewed and validated by Michael Cullen, P.Geo., of Mercator Geological Services, a Qualified Person as defined under NI 43-101 who is independent of the Company. This mineral resource estimate is an update of the first NI 43-101 mineral resource estimate released by the Company on February 14, 2012 (see press release February 14, 2012).
- Specific gravities were determined by Castillian for a representative number of rock and mineralization types using industry standard methods. A total of 1,387 determinations exist in the database. The average value for each modeled domain was applied to the block model. Specific gravities were further confirmed in testing of representative core samples by G&T Metallurgical Services, a division of ALS Metallurgy.
- Detailed geological logging and sectional interpretations by Castillian led to the development of three-dimensional (3D) domain models based mainly on lithological controls and partially on assay results. The wireframing resulted in a high grade envelope (approximately 2.0 g Au/t cut-off grade) within a lower grade silicic domain (approximately 0.5 g Au/t cut-off grade) that encompasses the bulk of the mineralization. These domains were utilized in the variography studies and in grade interpolation constraints. A footwall pyrite domain and a hanging wall argillic alteration domain were also wireframed to enable interpolation of local areas of mineralization and to provide possible exploration targets. The mineralization is cut by a series of mafic dikes that could not be individually wireframed, therefore a statistically derived dike model was constructed that was calibrated with available surface and historical underground geological information. The model prepared for the February 14, 2012 resource estimate was updated based on the new 2012 diamond drilling information.
- For the treatment of outliers each statistical domain was evaluated separately for gold and a combination of grade capping and search restrictions imposed on threshold values was used to restrict the influence of outliers. Capping only affected a small number of samples.
- The composite intervals selected were 2.5 metres. Grade capping was applied prior to compositing.
- A 3D geological block model was generated using GEMS© software. The block model matrix size is 15 metres x 5 metres x 10 metres. Ordinary kriging was used for all domains with inverse distance and nearest neighbour check models. The interpolation was carried out in multiple passes with increasing search ellipsoid dimensions. Classification for all models was based primarily on the pass number followed by an adjustment to the class model, based on the distance to the closest sample and kriged variance. The area in the model where historical mine workings exist was downgraded to inferred due to uncertainties about the location and extent of these workings. Confirmation of the historical stope location by 2012 Castillian drilling allowed the selection of blocks eligible for downgrading to be constrained to the immediate area surrounding the three dimensional modelled stopes. Insufficient data for copper was available in historical drill holes to allow for interpolation of copper grades in the model and therefore the total contained copper was omitted from this release.
- The reported mineral resources are considered to have reasonable prospects of economic extraction. A Lerchs Grossman optimized constraining shell was generated to constrain the potential open pit material. This shell was designed using design parameters and costs for comparable deposits, 86% recovery based on new metallurgical testing and historical plant performance and a gold price of US$1,400 per ounce which is equivalent to the three year moving average price. The constraining shell extends down to the 4,800 metre level, the deepest level developed in the historical mine at approximately 340 metres below surface.
- The rounding of tonnes as required by NI 43-101 reporting guidelines may result in apparent differences between tonnes, grade and contained ounces.
- Mineral resources that are not mineral reserves do not have demonstrated economic viability. The estimate of mineral resources may be materially affected by environmental, permitting, legal, title, taxation, sociopolitical, marketing, or other relevant issues.
- The quantity and grade of reported inferred mineral resources in this estimation are uncertain in nature and there has been insufficient exploration to define these inferred mineral resources as indicated or measured mineral resources and it is uncertain if further exploration will result in upgrading them to indicated or measured mineral resources.
SAMPLING, ASSAYING AND QUALITY CONTROL
All drill core in the Castillian diamond drilling program (NQ (47.6 mm), BQTK (40.6mm) and BQ (36.4mm)) was logged, photographed and then sawn 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 Chemex, with sample preparation done in Sudbury and analytical work done in Vancouver. All locations of ALS Chemex are ISO 9001:2000 certified. The entire sample received is weighed and crushed to ≥ 70% passing 2mm (10 mesh). 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 is initially analyzed using a four acid digestion ICP (inductively coupled plasma-atomic emission spectrometry) method. Any results for copper greater than 10,000 ppm are assayed further by a four acid digestion and "ore grade" ICP 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. Castillian also inserts external reference standards as well as blank granite drill core in each sample batch as a further external check.
QUALIFIED PERSONS
Dr. Bill Pearson, P.Geo., President and CEO of Castillian, who is a qualified person as defined by NI 43-101, has reviewed and approved the scientific and technical content of this press release. Pierre Desautels, P.Eng., Principal Resource Geologist, and Jay Melnyk, P.Eng., Principal Mining Engineer, both of AGP Mining Consultants and Qualified Persons under NI 43-101 who are independent of the Company, have prepared and authorized the release of the mineral resource estimates presented herein. The Castillian and historical diamond drill hole databases and geological model developed by Castillian were reviewed and validated by Michael Cullen, P.Geo., of Mercator Geological Services, a Qualified Person as defined under NI 43-101 who is independent of the Company.