The G-857 provides a reliable, low-cost solution for a variety of magnetic search and mapping applications. Single keystroke operation means the G-857 can be operated by non-technical field personnel and used in teaching environments. Utilizing the well-established proton precession method, the system allows for accurate measurements to be made with virtually no dependence upon variables such as sensor orientation, temperature or location.

The automated cycling option with long sensor cable and external power connection allows the surveyor to use G-857 as a base station instrument for measuring the diurnal changes in the Earth’s magnetic field. Optional GPS allows data to be stamped with time and Latitude/Longitude positions. Quickly and easily upload GPX waypoint survey routes to the GPS for in-field navigation using MagMap software. If you’re looking for a basic low-cost magnetometer with base station configurations, the G-857 Proton Magnetometer is the instrument of choice.


Features and benefits

  • Versatile: Use as a survey magnetometer or base station for diurnal corrections.
  • Economically Priced: Great for academic settings, small companies, or personal hobbies, as well as professionals in the oil and gas industry.
  • Great for Any Application: Well suited for mapping geological structures, mineral exploration, and search for industrial, environmental, or archaeological targets.
  • Easy to Operate: Designed for use by experienced and non-skilled personnel.
  • Rugged Weatherproof Construction: Works in extreme weather and temperatures.
  • Optional Integrated GPS with In-Field Steering: Data points can be stamped with GPS position and time.

Technical Details

G-857 Magnetometer Specification List

G-857 Magnetometer

  • Resolution: 0.1 nT.
  • Clock: Julian date, accuracy 5 sec. per month.
  • Tuning: Auto or manual, range 20,000 to 90,000 nT.
  • Gradient Tolerance: 1000 nT/meter.
  • Max Sample Rate: 0.6 Hz.
  • Read: Manual, or auto cycle for base station use.
  • Memory: 65,000 field or base station readings.
  • Display: Six-digit display of field/time, three-digit auxiliary display of line number, day.
  • Digital Output: RS-232, switch-selectable to 115200 baud.
  • Digital Input: Will accept external cycle command.
  • Physical: Console: L: 18 cm; W: 27 cm; H: 9 cm; Weight: 2.7 kg (7x10.5x3.5 in; 6 lb).
  • Sensor: DIA: 9 cm; L: 13 cm; Weight: 1.8kg (3.5x5 in; 4 lb).
  • Environmental: Meets specifications within 0° to +40°C (+32° to +105°F). Will operate satisfactorily from -20° to +50°C (-40 to +122°F).
  • Power: 12 Volt rechargeable Gel Cell.
  • Standard Accessories: Sensor, staff, chest harness, two sets of batteries, RS-232 cable, USB Serial adapter, operations manual, applications manual, MagMap software.
  • Options: External power/RS-232/sensor cable, rechargeable battery and charger set, Garmin® Oregon 600® GPS.
G-857 Magnetometer Shipping Weights & DIMS

Shipping Weights & DIMS

Contents Dimensions (L x W x H) Weight
Case 1 - G-857 Magnetometer 27in x 8in x 12in
69cm x 20cm x 31cm


  • Environmental: Find abandoned wells, pipes, and storage tanks quickly.
  • Archaeology: Perform basic magnetic archeology surveys.
  • Geology: Survey for regional variations in the magnetic field for mining and oil and gas applications.