Indonesia – exploration on the cusp of development

Mining and exploration in Indonesia present challenges that are technical, legal and social in nature. The country is currently developing regulations for its new mining law, so there is some uncertainty, albeit within a well-defined legal framework.

Indonesia provides numerous opportunities for exploration, and SRK is currently involved in several major projects there, mainly concerned with preparing JORC resource statements on coal, gold, laterite nickel and copper deposits. This active tectonic environment with volcanic arcs from the Cretaceaous to Recent periods overlying Late Paleozoic to Mesozoic basement rocks, contain some world class orebodies.

Asia Minerals Corporation recently engaged SRK Indonesia to assess the potential of small manganese deposits in Nusa Tengara Timor (NTT) in West Timor to feed a proposed new, local processing facility to comply with the new mining law. This will require a resource of about 2.5 million tonnes.

The opportunity is significant; there are more than 50 known manganese sites in NTT, where the ore is currently extracted by artisanal mining techniques and exported as unprocessed product.
The individual deposits are small, spread across extensive areas. Several economically-viable, near-surface deposits are commonly pursued concurrently to provide sufficient tonnes for processing. The advantage is that deposits are generally high-grade with low impurities.

The key to discovering and exploiting such deposit fields is in understanding the deposit genesis for targeting, and following a disciplined exploration methodology. In Timor, the deposits are located in sedimentary rock deposited on the seafloor, subsequently displaced across the region, with numerous thrust faults and remnant mud volcanoes. Currently, there is no model of seafloor manganese deposits that fits well with the Timor occurrences.

Developing exploration skills

In collaboration with geologists from Asia Minerals Corporation and other advisors, SRK hosted a workshop in Jakarta to advance the understanding of manganese deposits and generate an exploration program that would address the physical and climatic aspects of NTT in West Timor and provide the highest probability of success in defining manganese deposits to about 50m depth along strike from known occurrences.

The workshop identified and mapped those occurrences, and prioritised them for field inspection. The mapping program outlined criteria and methods to determine the characteristics of the deposits and to help develop a genetic model for NTT manganese. It identified remote sensing requirements, geophysical methods, including potential field and active electrical methods, and geochemical methods. The group defined a test area currently accessible under exploration licence, where these techniques can be employed and where geometry is either known or can be reasonably inferred. The results from testing these techniques will guide future program development.

SRK will continue its involvement through field reviews, regular exploration program audits, and assessment of exploration results. Over a 2-day workshop, Asia Minerals Corporation learned about the key data collection required to assess current exploration areas and generate exploration models, adopted a methodology to assess the entire eastern NTT region for exploration potential, and an immediate program to assess its current development licence for preliminary resource estimation. In the process, it gained a committed team aware of the different components that an exploration program needed and the inter-relationships that deliver exploration success.

Peter Williams:

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