require frequent inner tube removals. Diamond core drilling has been used to extract core samples from depths of up to 2,500 metres and is the only type of drilling that can be used in virtually all ground conditions. Designed specifically for the resource exploration industry, diamond drilling is the most versatile of all drilling methods and the only method that generates core samples. A core sample is a cylindrical section of rock, usually three centimetres to seven centimetres in diameter, and generates reliable samples for accurate geochemical assaying and orientation assessments along the depth of the drill hole. R everse Circulation Drilling R everse circulation drilling, which can be used on softer rock, requires dual tube drill rods. R everse circulation drilling uses pneumatic force to cut and hammer a hole into the rock using a tungsten-studded button bit. Drilling fluid is circulated down to the drill bit via the annular space that exists between the inner and outer tubes of the dual-walled drill string; as the drilling fluid passes through the drill bit, it picks up the rock cuttings at the face of the drill bit which are conveyed to the surface in the inner tube. R everse circulation drilling is cheaper and faster than diamond drilling, although it is typically only employed up to depths of 500 metres below surface and produces fragments and chips of broken rock, yielding less geological information than from diamond core drilling. R otary Air Blast Drilling R otary air blast drilling is an inexpensive method of rotary drilling. The type of drilling is useful for geological sampling in the earliest drilling stages of exploration drilling, and is well-suited for hard rock. Cutting samples are blown to the surface using compressed air that is directed through the inside of the hollow drill rods, through the drill bit, and up the annulus between the wall of the hole and the exterior of the drill pipe. R otary air blast drilling is generally used in shallow hole systems to depths no greater than 50 metres. R otary Drilling R otary drilling, in its simplest form, uses an air or water stream pumped to the face of the drill bit to deliver drill cuttings to the surface between the wall of the hole and the exterior of the drill pipe. This form of drilling is used to create a stable hole that can be used for a variety of purposes, including to drill water wells, oil and gas wells, groundwater monitoring wells (piezometers), monitoring wells, seismic testing wells, and to allow for sampling of particular formations, such as uranium deposits. Down-the-hole Hammer Drilling Down-the-hole hammer drilling is the fastest method of penetrating hard rock formations. This method is used to create a stable hole that can be used for a variety of purposes, including water wells, groundwater monitoring wells (piezometers), monitoring wells, seismic testing wells, blast holes, and to sample particular mineral deposits, within hard ground conditions. Direct Circulation Drilling Direct circulation drilling involves circulation of drilling fluid in the tube of the drill string which is then circulated to the surface, together with cuttings, via the space between the width of the hole and the exterior of the drill rod. Contract Drilling Customers MEG classifies companies undertaking minerals exploration into three main groups: (i) major mining companies, (ii) intermediate mining companies and (iii) junior mining companies. Major mining companies Major mining companies are defined as large mining companies with global operations and annual mining- related revenues of greater than US$500 million. Due to their size and financial resources, major mining companies are typically able to develop or operate a large mine without external financing. In many instances, 21