Robust intersects further high grade massive sulphide in Romang Island project

By Ruli Setiawan

ASX-listed Robust Resources Limited announced Wednesday the assay results from diamond drill hole LWD 360 from the Batu Mas Deeps prospect on Romang Island.

Following the discovery of high-grade sulphide mineralization at the Batu Mas Deeps prospect, as announced early this month, the company has intersected further massive sulphides from a second hole LWD 360, further confirming the potential of the Romang Island project.

Robust said in a statement that assay results for LWD 360 have now confirmed a broad zone of rich and intense polymetallic breccia style mineralization over an 83-meter intersection that has a core of massive sulphides 8 meters thick. The results from LWD 360 include:

- 83m at 7.01% combined base metals and 0.67 g/t AuEq? from 77m
(0.58% Cu, 3.51% Pb, 2.92% Zn, 0.18 g/t Au, 26g/t Ag) including:
- 53m at 10.24% combined base metals and 0.91 g/t AuEq from 97m
(0.84% Cu, 5.22% Pb, 4.17% Zn, 0.23 g/t Au, 36g/t Ag) including massive sulphides:
- 8m at 37.85 % combined base metals and 2.33 g/t AuEq from 97m
(0.89% Cu, 25.82% Pb, 11.14% Zn, 0.29 g/t Au, 108 g/t Ag)

LWD 360 is collared 40 meters west of LWD 352, which was reported last week to have an open-ended intersection of 102.8 meters at 5.71% base metals, including a massive sulphide zone of 6 meters at 54.9% basemetals.

The potential of the Batu Mas Deeps mineralization is graphically demonstrated by the 3D IP and resistivity geophysics. The mineralized intersections are interpreted to be associated with shallow dipping resistivity anomalies.

If these anomalies demonstrate continuations of the mineralization intersected so far, then the size of the mineralized breccias may be very large and the potential for further discovery at depth will be highly likely, Robust said.

The grades of the Batu Mas Deeps massive sulphide mineralization from LWD 120, LWD 352 and LWD 360 compare favorably with historical, current and proposed high-grade underground lead-zinc-silver and polymetallic deposits elsewhere. Some examples of the grades reported for this type underground mine/deposit are:
? The famous Broken Hill South underground mine in Australia, produced 34 million tons of ore grading 25.5% combined base metals and 230 g/t Ag to a depth of 1.7kms before it closed in 1992.
? Rosebery is an underground VMS mine in Tasmania has been operating since 1893. In 2004 it was producing with mineral reserves of 5.3 million tons at 15.7% combined base metals, 1.7 g/t Au and 123 g/t Ag. It remains operational to this day.
? The undeveloped Anjing Hitam deposit in Sumatra, Indonesia is considered to be an attractive underground mining and development proposition. It has a mineral resource (2004) of 7.7 Mt at 25.8% combined base metals and 12 g/t Ag.

The reason for this comparison of grades is that if the Batu Mas Deeps exploration is successful in delineating even a modest tonnage at or near to the grades obtained so far, then early development and extraction by underground mining of high-grade ore might be an option to enhance the economics of the Lakuwahi project as a whole, Robust explained.

It should be noted that it was the discovery of the high-grade Zone VII at the Porgera Mine in PNG that transformed the economics of that project Zone VII was mined first from underground and then a large open pit extracted the adjacent lower grade ore. This underground mine was highly profitable and funded much of the development capita for subsequent open pit mining.

It should also be noted that for Batu Mas Deeps there has been insufficient exploration to estimate a mineral resource and there remains uncertainty that further exploration will result in the estimation of a mineral resource, Robust is now prioritizing drilling the Batu Mas Deeps domain using two dedicated diamond drill rigs.

Robust?s Managing Director Gary Lewis commented: ?The latest drilling results from Batu Mas Deeps further confirms the exceptional potential of our Romang Island project. LWD 360 represents one of the best intersections from our drilling program on Romang Island, and we have now received three massive sulphide hits from the same number of drill holes.?

?3D IP and Resistivity data has been recently reprocessed using more advanced modeling algorithms, and this has allowed us to look at deeper structures. Based on these outstanding results, drilling at new holes is currently underway, utilizing two dedicated owner-operated diamond drill rigs, and we are confident this will further unlock significant potential,? he added.

Editing by Reiner Simanjuntak