The ML-Compass (US Patent number 6701631; Monteiro and Laamanen, 2004 (Authors) – intellectual property of Vale S.A.) was developed to overcome the problem of collecting structural data in locations where the magnetic field is distorted, where conventional magnetic compasses are rendered useless (such as with underground mines, highly magnetic rocks or ore, locations with high magnetic inclination, and so on).
The ML-Compass can be used underground and in open pit environments and was also tested in high latitude areas. It is simple to use and results are obtained in real-time. The ML-Compass was originally developed in 1999 to be used during structural mapping of strongly magnetic ore (1D Mine - Thompson Nickel Belt). Its use resulted in a better understanding of the ore deposit spatial patterns (internal and external), including its extensions, allowing the construction of a better constrained mineral envelope that was later validated by mining development.
Recently this unique tool was used in Northern Canada to acquire reliable structural data from highly magnetic nickel sulphide-bearing targets. Drilling at these targets have only included non-oriented core, and the Structural Inversion Method© was used in conjunction with the ML-Compass to establish the best geometrical scenario to drill-test the extension and connectivity of previously intersected sulphide lenses.
Later in 2013, this compass was also used in the Carajas Mineral District in Brazil to conduct structural mapping in an iron ore project. The results assisted in determining the most likely fold architecture that was controlling the iron ore. This geometry is now constraining the drilling pattern at that site.