Petrographic Characteristics of Porphyry Indicator Minerals From Alkalic Porphyry-libre
ASX: AZS 28 August 2013 PORPHYRY COPPER POTENTIAL IDENTIFIED
Transcript of ASX: AZS 28 August 2013 PORPHYRY COPPER POTENTIAL IDENTIFIED
ASX: AZS 28 August 2013
PORPHYRY COPPER POTENTIAL
IDENTIFIED AT CASCADA
Large Copper & Gold Zones Confirmed Azure Minerals Limited (ASX: AZS) (“Azure” or “the Company”) is pleased to
provide an update on the Company’s Cascada copper-gold-silver project located in
the Mexican state of Chihuahua.
Over the past month the Company received all outstanding assays and completed
geological interpretation of the Cascada copper deposit. This has resulted in
definition of the major mineralised structures, delineation of the mineralised
envelopes for both copper and gold zones, and identification of underlying porphyry
copper potential.
KEY POINTS
Results confirm that Cascada hosts two large, overlapping copper and gold
mineralised systems
Wide zones of high grade copper mineralisation are surrounded by widespread
gold mineralisation
Both copper and gold zones remain open at depth and along strike
High sulphidation epithermal alteration system indicates likelihood that
mineralisation is sourced from an underlying porphyry copper system
Detailed, deep-seeking Induced Polarisation (IP) survey will commence in early
September to target Cascada extensions and porphyry system
COPPER ZONE
High grade copper-gold-silver zone has true widths up to 30m with grades
averaging +5% CuEq and peak grades of +40% Cu
Surrounding copper-mineralised envelope has significant bulk tonnage potential
Mineralisation is mostly chalcocite – a high tenor copper sulphide mineral
GOLD ZONE
Extensive gold-rich envelope surrounds Cascada copper deposit
Gold zone increases in grade and width towards the west with bulk tonnage
deposit potential
SIGNIFICANT MINERALISED DRILL INTERCEPTS
COPPER ZONE
DRILL HOLE HIGH GRADE
COPPER ZONE COPPER MINERALISED
ENVELOPE
APR-DD-087 35.9m @ 4.5% CuEq1 70.0m @ 2.6% CuEq
APR-DD-089 32.9m @ 6.3% CuEq 129.0m @ 2.9% CuEq
APR-DD-091 29.4m @ 7.4% CuEq 61.5m @ 4.1% CuEq
APR-DD-092 32.4m @ 3.7% CuEq 56.0m @ 2.9% CuEq
APR-DD-093 40.9m @ 5.5% CuEq 101.5m @ 3.0% CuEq
APR-DD-098 19.0m @ 6.0% CuEq High grade zone only
APR-DD-104 6.8m @ 2.6% CuEq 49.6m @ 1.4% CuEq
GOLD ZONE
DRILL HOLE GOLD MINERALISED ENVELOPE
APR-DD-087 118.9m @ 0.7g/t Au
APR-DD-090 120.8m @ 1.0g/t Au
APR-DD-091 64.4m @ 1.9g/t Au
APR-DD-092 101.1m @ 1.0g/t Au
APR-DD-093 113.8m @ 2.4g/t Au
APR-DD-095 90.6m @ 0.9g/t Au
APR-DD-100 63.6m @ 1.3g/t Au
APR-DD-104 104.9m @ 0.9g/t Au
Managing Director, Mr Tony Rovira, commenting on the Cascada results, stated:
“The drilling program at Cascada has exceeded our expectations and will result in a
significant change in the scale of proposed operations at the Promontorio project.
“Not only have we delineated a large body of high grade copper, gold and silver
mineralisation, but we have now also identified a substantial zone of gold
mineralisation that may be of economic significance in its own right. Both the high
grade copper zone and the surrounding gold system remain open along strike and at
depth and are exciting targets for future exploration.
“The next phase of exploration will commence almost immediately and comprise an
Induced Polarisation survey to highlight mineralised extensions and the underlying
porphyry copper potential. I expect this survey to be completed within the current
quarter and the information will be used, in conjunction with the recent drill data, to
define the next generation of drill targets at this very exciting project.”
1 See Appendix for Copper Equivalency (CuEq) Statement
RESULTS
Figure 1 provides a plan view of drill hole locations, Figures 2-5 are cross sections of
recent drilling, and details of drill holes and significant copper and gold mineralised
intercepts are contained Tables 1, 2 & 3.
Data interpretation of both the recent drill program and historical drill data has
identified two separate but overlapping mineralised systems at Cascada.
Copper Zone
The high grade copper-gold-silver mineralisation is centrally located within Cascada’s
intense silica-sericite alteration system. Mineralisation was intersected in multiple drill
holes on cross sections spaced at 15-20 metre intervals over a strike length of 100
metres. The high grade copper zone is up to 30 metres in true width, strikes east-
west, and appears to dip steeply to the north with a steep westerly plunge.
Sulphide mineralisation is dominated by widespread, moderate to abundant,
disseminated chalcocite and lesser amounts of enargite and chalcopyrite. It is hosted
within intensely silicified volcanic rocks, indicating that strong high sulphidation
epithermal alteration occurred during the mineralising phase, which is typical of a
porphyry copper mineralising event.
The most westerly hole at Cascada, APR-DD-100, is now known to have been
collared too far to the north and drilled over the top of the west-plunging high grade
copper zone. However it drilled a long gold intercept through the northern flank of the
surrounding gold mineralised system with almost the entire drill hole length of 205
metres returning anomalous gold grades.
Further to the west the mineralised system is covered by post-mineralisation volcanic
rocks. Several historical holes drilled in this area, including three by Azure,
intersected anomalous mineralisation, including:
CP93011 35m @ 2.3g/t Au from 3.1m; and
38m @ 0.5g/t Au from 89.9m;
CP93012 128m @ 0.7g/t Au from surface to end of hole
Strongly anomalous copper mineralisation up to 1.65m @ 2.55% Cu was intersected
in CP93012, although the previous explorer only assayed every fifth sample.
Azure believes that this western area has strong potential to significantly expand the
Cascada high grade copper mineralised system, together with strong likelihood for a
large bulk tonnage gold deposit.
Gold Zone
Surrounding the high grade copper-gold-silver zone is a widespread halo of
moderate grade gold mineralisation. Gold mineralisation with anomalous to economic
grades is pervasive throughout the area, commencing at or close to surface and
often extending to near the ends of the holes. Grades and widths of this gold zone
increase towards the west, with the zone extending over a horizontal (possible true)
width in excess of 100 metres on the westernmost section.
This along-strike grade and width variation is demonstrated by the following
mineralised intercepts.
Western Cascada Zone:
- APR-DD-100: 63.6m @ 1.3g/t Au from 13 metres
and 52.0m @ 0.9g/t Au from 150 metres
- APR-DD-104: 104.9m @ 0.9g/t Au from 21 metres
- APR-DD-091: 64.4m @ 1.9g/t Au from 32 metres
- APR-DD-092: 101.1m @ 1.0g/t Au from 31 metres
- APR-DD-093: 113.8m @ 2.4g/t Au from 25 metres
Central Cascada Zone:
- APR-DD-087: 119.0m @ 0.7g/t Au from 12 metres
- APR-DD-088: 23.7m @ 1.5g/t Au from 72 metres
- APR-DD-089: 129.0m @ 0.7g/t Au from 41 metres
- APR-DD-090: 120.8m @ 1.0g/t Au from 35 metres
- APR-DD-094: 87.5m @ 0.8g/t Au from surface
- APR-DD-095: 90.6m @ 0.9g/t Au from surface
- APR-DD-096: 102.0m @ 0.5g/t Au from surface
Eastern Cascada Zone:
- APR-DD-054: 137m @ 0.5g/t Au from 48 metres
- APR-DD-097: 39.8m @ 0.6g/t Au from 23 metres
- APR-DD-098: 52.5m @ 0.8g/t Au from 22 metres
- APR-DD-099: 86.4m @ 0.5g/t Au from 20 metres
These drill intercepts indicate excellent potential for a large, bulk-tonnage gold
deposit and Azure will follow up this target with further drilling.
NEXT STAGE
An Induced Polarisation (IP) geophysical survey will be conducted over the Cascada
area. As the two mineralised systems at Cascada (copper-gold-silver & silica-rich
gold) are likely to have formed from a single porphyry copper mineralising event, and
such systems can be very large, the IP survey is designed with three aims:
1. To identify accumulations of sulphide mineralisation representing extensions of
the high grade copper zone;
2. To identify zones of intense silica-rich alteration representing the gold zone; and
3. “Look” deeper and under cover for the feeder zones and the porphyry source of
mineralisation.
This IP survey is expected to be completed by this quarter’s end and will be followed
by the next round of drilling.
Figure 1: Cascada drill hole location plan and surface projection of gold
mineralised zone
BACKGROUND
The Promontorio and Cascada deposits both form separate parts of a high-
sulphidation, epithermal system where base and precious metal mineralisation
comprises massive, semi-massive and disseminated copper sulphides hosted in
vuggy silica and silicified host rocks.
High sulphidation epithermal deposits form above porphyry copper bodies with
feeder zones connecting the porphyry and the overlying epithermal system. These
types of deposits are common in northern Mexico and south-western US.
Azure believes that beneath Cascada and Promontorio is a porphyry copper body
which was the source of the copper, gold and silver mineralisation and is likely to be
mineralised in its own right. This makes the Promontorio Project an exciting
porphyry copper exploration target.
Future exploration will follow up the depth extensions of the Cascada mineralised
system to search for the feeder zone or connection to the porphyry copper target.
Azure is currently applying geochemical and geophysical vectors to direct our
exploration towards the mineralising source.
Promontorio contains a JORC-compliant Mineral Resource2 (Indicated + Inferred) of:
Resource
Classification Tonnes
CuEq
(%)
Cu
(%)
Au
(ppm)
Ag
(ppm)
Reported Above 0.5% CuEq cut-off
Indicated 610,000 4.4 2.7 1.7 56
Inferred 230,000 3.3 1.8 1.5 56
Total 840,000 4.1 2.5 1.6 56
-ENDS-
For further information, please contact: Tony Rovira Managing Director Azure Minerals Limited Ph: +61 8 9481 2555
Press / Investor Relations Victoria Thomas Six Degrees Investor Relations Ph:+61 3 9645 7567
or visit www.azureminerals.com.au
2 Details of the resources classification and estimation methodologies are contained in Azure’s ASX announcement,
released on 10th May 2013.
Figure 2: Cross section 382,375mE
Figure 3: Cross section 382,390mE
Figure 4: Cross section 382,410mE
Figure 5: Cross section 382,430mE
Competent Person Statement: Information in this document that relates to Exploration Results and Mineral Resources is based on information compiled by Mr Tony Rovira, who is a Member of The Australasian Institute of Mining and Metallurgy. Mr Rovira is a full-time employee of Azure Minerals Limited. Mr Rovira has sufficient experience which is relevant to the style of mineralisation and type of deposit under consideration and to the activity which he is undertaking to qualify as a Competent Person as defined in the 2004 Edition of the “Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves”. Mr Rovira consents to the inclusion in the documents of the matters based on his information in the form and context in which it appears.
APPENDIX
Copper Equivalency Statement:
• Copper Equivalent (CuEq) was based on the following assumed metal prices that were guided by the three year averages at the data cut-off date: US$3.25/lb for Cu, US$1,450/oz for Au and US$27.50/oz for Ag.
• The CuEq grade accounts for the following metal recoveries, which were based on metallurgical testwork completed on the adjacent Promontorio deposit by independent metallurgical laboratories AMDEL and Ammtec, under the supervision of Coffey Mining Pty Ltd: 97.9% for Cu, 93.4% for Au, and 97% for Ag.
• It is Azure’s belief that all elements included in the metal equivalent calculation have a reasonable potential to be recovered.
• The following formula was used to calculate the Copper Equivalent grade: CuEq (%) = (Cu% x 0.979) + (Au (g/t) x 0.6077) + (Ag (g/t) x 0.0120)
Drilling and Sample Analysis Statement: Detailed geological logging is undertaken with recording of lithology, alteration, veining, mineralisation and mineralogy. Primary samples are all HQ-size half core. Secondary (duplicate) HQ-size quarter core samples are collected at nominal 20m intervals and submitted for comparison checks. Geological controls and orientations of the mineralised zone are unknown at this time and therefore all mineralised intersections are reported as “intercept length” and may not reflect true width. Sampling is based upon geological boundaries with minimum sample length of 0.2m and maximum sample length of 1.0m. Reported copper mineralised intersections are based on intercepts using a nominal 0.2% copper grade cut-off and a 0.5% Copper Equivalent cut-off. Reported gold mineralised intersections are based on intercepts using a nominal 0.2g/t gold cut-off. All reported assays have been length-weighted. No top cuts have been applied. High grade intervals internal to broader mineralised zones are reported as included zones. Sample preparation was undertaken by ALS-Chemex (Hermosillo) and analysed by ALS-Chemex (Vancouver) using methods ICP61 and OG62 (for silver and base metals) and Fire Assay methods AA-23 and GRA-21 for gold.
Certified Reference Standards and blank check samples are routinely inserted at 20m intervals and also immediately following visually identified mineralised intercepts to provide assay quality checks. Review of the standards and blanks are within acceptable limits. Drill hole collar locations are initially surveyed by handheld GPS and definitively surveyed by differential GPS following completion of the drilling program. Downhole surveys are undertaken at 30m intervals by gyroscope.
TABLE 1: Drill Hole Information
HOLE No. NORTH
(mN) EAST (mE)
ELEVATION (mASL)
AZIMUTH DIP TOTAL DEPTH
LOCATION
APR-DD-088 3,146,359.1 782,389.5 1,963 176 -60 190.30 Cascada
APR-DD-089 3,146,359.1 782,389.5 1,963 181 -45 178.20 Cascada
APR-DD-090 3,146,359.1 782,389.5 1,963 181 -35 183.90 Cascada
APR-DD-091 3,146,341.0 782,376.0 1,966 180 -60 149.80 Cascada
APR-DD-092 3,146,341.0 782,376.0 1,966 180 -50 163.30 Cascada
APR-DD-093 3,146,341.0 782,376.0 1,966 180 -40 150.80 Cascada
APR-DD-094 3,146,341.7 782,409.8 1,982 182 -60 205.20 Cascada
APR-DD-095 3,146,341.7 782,409.8 1,982 178 -68 194.30 Cascada
APR-DD-096 3,146,341.7 782,409.8 1,982 179 -49 145.20 Cascada
APR-DD-097 3,146,261.0 782,430.0 1,984 360 -40 129.90 Cascada
APR-DD-098 3,146,260.0 782,430.0 1,984 360 -60 121.60 Cascada
APR-DD-099 3,146,267.0 782,430.0 1,983 360 -75 145.70 Cascada
APR-DD-100 3,146,233.0 782,361.0 2,027 360 -60 214.50 Cascada
APR-DD-101 3,146,489.8 782,663.5 2,044 215 -65 100.70 Rojo Grande
APR-DD-102 3,146,489.0 782,663.0 2,044 215 -30 76.10 Rojo Grande
APR-DD-103 3,146,359.5 782,448.8 1,999 180 -50 154.60 Cascada
APR-DD-104 3,146,340.0 782,376.0 1,966 180 -30 138.20 Cascada
APR-DD-105 3,146,339.6 782,299.7 2,018 360 -60 150.00 Cascada NW
TABLE 2: Significant Copper Mineralised Drill Intercepts from Cascada
HOLE FROM TO INTERCEPT
LENGTH (m) CuEq (%)
Cu (%)
Au (ppm)
Ag (ppm)
APR-DD-088 85.80 92.00 6.20 2.67 0.65 2.62 36
and 130.00 136.45 6.45 0.77 0.62 0.12 8
APR-DD-089 40.20 62.10 21.90 1.41 0.65 1.00 12
and 67.85 100.70 32.85 6.30 4.59 0.81 109
and 123.35 163.05 39.70 2.67 1.85 0.80 31
APR-DD-090 30.00 65.57 35.57 1.66 0.74 1.17 19
and 69.70 95.71 26.01 2.68 1.64 1.14 31
APR-DD-091 39.15 48.84 9.69 3.03 1.17 2.44 34
and 72.70 102.05 29.35 7.43 4.39 2.99 110
APR-DD-092 32.00 40.62 8.62 4.67 2.40 2.56 64
and 73.72 106.13 32.41 3.74 1.94 1.38 84
APR-DD-093 32.05 45.61 13.56 2.57 0.90 2.25 27
and 64.60 105.50 40.90 5.49 2.00 4.87 48
APR-DD-094 49.55 61.90 12.35 3.94 2.69 1.66 25
and 118.40 125.43 7.03 2.07 1.73 0.36 14
and 169.25 174.00 4.75 2.26 1.48 1.07 14
APR-DD-095 41.30 45.90 4.60 1.30 0.13 1.27 20
APR-DD-096 80.80 100.40 19.60 1.91 1.42 0.53 16
and 122.10 125.65 3.55 4.23 3.35 0.71 44
APR-DD-097 40.15 50.20 10.05 2.19 1.40 1.10 13
APR-DD-098 52.15 71.15 19.00 6.00 4.90 1.30 35
APR-DD-099 52.40 84.10 31.70 1.64 1.14 0.55 15
APR-DD-100 187.42 200.75 13.33 1.57 0.40 1.76 9
APR-DD-101 Rojo Grande Prospect – No significant copper intercept – gold intercept only
APR-DD-102 Rojo Grande Prospect – No significant copper intercept – gold intercept only
APR-DD-103 No significant copper intercept
APR-DD-104 28.15 41.17 13.02 1.52 0.47 1.53 11
and 73.58 88.61 15.03 1.55 1.31 0.26 10
and 111.28 118.10 6.82 2.58 0.63 2.94 15
APR-DD-105 Cascada NW Zone -No significant copper intercept
TABLE 3: Significant Gold Mineralised Drill Intercepts from Cascada
HOLE FROM TO INTERCEPT LENGTH (m) Au (ppm) Ag (ppm)
APR-DD-088 72.30 96.00 23.70 1.49 16
APR-DD-089 41.20 170.15 128.95 0.72 42
APR-DD-090 35.00 155.80 120.80 0.95 14
APR-DD-091 32.17 96.55 64.38 1.92 58
APR-DD-092 31.15 132.24 101.09 0.96 36
APR-DD-093 25.00 138.80 113.80 2.43 25
APR-DD-094 0.0 87.50 87.50 0.83 9
APR-DD-095 2.50 93.14 90.64 0.94 9
APR-DD-096 0.0 102.30 102.30 0.48 9
APR-DD-097 22.75 62.58 39.83 0.57 10
APR-DD-098 21.85 74.35 52.50 0.82 17
APR-DD-099 19.60 106.00 86.40 0.47 10
APR-DD-100 13.00 76.65 63.65 1.27 24
and 149.70 201.65 51.95 0.90 8
APR-DD-101 3.40 12.85 9.45 0.40 11
APR-DD-102 7.10 21.80 14.70 0.45 7
APR-DD-103 No significant gold intercept
APR-DD-104 21.20 126.10 104.90 0.89 9
APR-DD-105 Cascada NW Zone -No significant gold intercept