Not Making Toasters Part Two
Not Making Toasters – Part Two
Best practice exploration is a multi-disciplined, multi-staged process that takes time. It also takes a mindset of expenditure commitment and exploration perseverance; and it takes a blend of lateral thinking and adaptation, attention to detail and due diligence, and pragmatism.
I’ll confine the discussion to “pure” exploration, so as to exclude activities that are considered part of pre-mining development (resource drilling and metallurgy for example) and mining development (pit design and waste management for example). These are not in my field of experience.
Exploration can be broken into three main phases:
- Reconnaissance Exploration: The very first forays of activity in a new project area. The objective is to prove the concept of the project. If the company is looking for gold, are the rocks the right type? Are there old gold workings? Are there large structures that might be potential sites for gold mineralisation?
- Target Generation Exploration: A series of activities all designed to identify (find) specific areas of interest. The objective is to find the first signs of mineralisation (direct or indirect) that warrants further exploration.
- Target Testing Exploration: A series of activities all designed to test (refine) specific areas of interest. The objective is to commence the delineation of mineralisation that might represent an economic deposit.
Find – Refine – Define or Resign
Here’s my set of four rules for exploration:
Rule 1: Test the entire project area first with the least expensive [low cost per unit area] but most effective tool(s). By this, the company gets a handle on the general prospectivity of the entire project area.
Think: Geophysical survey covering an entire project, as an example.
Rule 2: Steadily reduce the area of interest. The purpose of each successive phase of exploration is to reduce the search area. The exploration should become increasingly focused in an increasingly smaller area (prospects/targets). Exploration and logistic efficiencies are achieved. The tools/methods that are deployed tend to be more expensive with each phase.
Think: Grid soil geochemical survey covering a large part of the area that has been identified as potentially hosting gold mineralisation, as an example.
Rule 3: Identify and define targets and test them. Onca a target is defined, there is a strong case, if not an obligation, to test it.
Think: RC drill program covering an arsenic soil geochemical anomaly within the grid soil geochemical survey area, as an example.
Rule 4: No targets – drop the project. If exploration identifies no target, what’s the point of keeping the project, especially if there are holding costs, or the company is farming in?
Start wide. End small
Low cost per square kilometre to high cost per square kilometre
Reconnaissance Exploration
The purpose of Reconnaissance Exploration is to prove the concept of the project. A project may have been acquired for its gold potential. This concept should be tested and, hopefully, verified.
What are the exploration tools/methods of Reconnaissance Exploration? And what are the strategies?
Exploration companies typically take two pathways with its Reconnaissance Exploration:
- Remote sensing (quite literally meaning that the sensor [tool] is “remote” from the project).
- Ground verification (a preliminary “on-ground look” at the project area).
Remote sensing exploration includes the acquisition of satellite imagery. There are dozens of different types of satellite images. The satellites collect data at different wavelengths. The data, presented as imagery, can be arbitrarily given colours (blue-green-red). The imagery will very commonly require expert interpretation. The objective is to identify areas of colour (or even grey shade) contract on the image that may relate to geological areas of interest.
Most exploration companies will conduct some form of airborne geophysics as part of their Reconnaissance Exploration.
The most common airborne geophysics survey type used by exploration companies during Reconnaissance Exploration is magnetics and radiometrics. It is cheap per square kilometre. You’ll see this survey combo being used very frequently. Abbreviated to AMAGRAD, these surveys are performed under a service agreement by dedicated airborne geophysics survey service companies.
AMAGRAD is often combined with digital terrain modelling (DTM) which very precisely creates 3D landscape imagery.
The benefits of AMAGRAD are:
- There is usually no requirement of a landowner access agreement (though notification is required);
- The program is almost entirely outsourced so there is very little required of the explorer;
- The survey can cover as much of the project areas as needed; and
- The survey can be quick.
There are a number of other airborne geophysical survey types used by explorers during Reconnaissance Exploration. Two common types include, gravity surveys, and Versatile Time Domain Electromagnetics (VTEM).
VTEM is significantly more expensive to conduct per unit area than AMAGRAD, gravity and DTM, and for this reason, is commonly deployed as a second phase Reconnaissance Exploration tool or is made part of the Target Generation Exploration Phase.
This next point is very important. It is very rare that an airborne geophysical survey does not produce some form of anomaly. In fact, airborne geophysical surveys almost always generate anomalies.
Reconnaissance geophysical surveys almost always generate anomalies and therefore, areas of interest
Because of this, ground verification (or ground truthing) is an import additional pathway in the Reconnaissance Exploration phase.
Ground truthing is needed to follow-up Reconnaissance geophysics
Ground truthing typically involves hopping in a four-wheel drive and spending some time on the ground. The principal activity is geological mapping and sampling.
As the explorer is on the ground, it will need to check access permissions, contacting a cocky and/or Traditional Owners, for example.
Geological mapping is conducted by geologists aided by a handheld GPS. The purpose is to walk across as much of the project area as possible to record the rock types, alteration, structures, and mineralisation. Notes are made and maps are produced. This work is not often considered “price sensitive” and as such is rarely the stand-alone subject of an ASX announcement.
The other purpose of mapping is to collect rock chip, stream and/or soil samples for multi-element analysis. Not all mineralisation is “obvious” in outcrop. Gold and silver mineralisation, for example, is not obvious at all. If copper mineralisation has been weathered and the “outcrop is blue-green” then the job is easier.
The point is this. The geologist will take many samples (typically more than 50 or so per program) whether he/she sees mineralisation or not.
The samples are submitted to a laboratory for analysis. It is now that the results may be considered “price sensitive” and an ASX announcement may become justified.
As well as the exploration activities described above, there are vitally important non-exploration activities that play out during the early stages of a project. These are to-do with the potentially prickly topic of [authorised] ground access. Without ground access very little exploration can take place.
Depending on the location of the project area, and status of the ground, access may be granted via one or all of the following:
- The relevant state government authorities (by way of awarding of tenure).
- Traditional Owners (TO’s) often with the assistance of Traditional Land Councils (by way of Exploration Deed).
- Surface rights owner e.g. Pastoral Lease holder (by way off a land access agreement).
On occasions, a landowner may allow an exploration company to conduct airborne surveys ahead of a formal access agreement. On rarer occasions, limited ground-based Reconnaissance Exploration may be allowed by the landowner. On this, there is no set pathway.
Land access matters go hand in hand with Reconnaissance Exploration
Whatever the first phase exploration tool is used (are used) the end result is almost aways the recognition of an area, or areas of interest.
The end-product(s) of Reconnaissance Exploration is typically a series of project-wide plans that show satellite/airborne geophysical anomalies, a primarily project-wide geological interpretation, and broad, and geochemical anomalies areas (broad if stream sampling; small if rock chip sampling).
Project-wide maps are generated in Reconnaissance Exploration
Broadly defined geophysical, geological, and geochemical areas are recognised
In Not Making Toasters – Part Three I will describe Target Generation Exploration and Target Testing Exploration.
