Typical Ranges of Resistivities for Common Materials


Electrical Resistivity Imaging (ERI) is a fantastic geophysical method for subsurface exploration and delineation (it certainly is our favorite!). In this article, we want to focus more on the “geo” part of geophysics and take a look at some resistivity values for common materials.


You see, ERI works best when you have a good knowledge of the geology of your survey area. In fact, when we’re helping new customers design their survey, or helping someone in the field—the geology of the area is one of our first questions.


Furthermore, if you have a good idea of resistivity ranges of the materials you’re looking at, you can easily put together the story of your survey. Something that may look suspicious in your survey data could actually just be normal geology (and vice versa). Knowing this information up front could save you a lot of time later!


There are many factors that affect a material’s resistivity. Resistivity is affected by natural geology, hydrogeology, mineralogical composition, porosity, temperature, pressure, water saturation, dissolved electrolytes, and other factors.


Typical Ranges of Resistivities for Common Materials
Rock/Material Type Resistivity Range (Ωm)
Alluvium 1 - 1,000
Basalt 10 - 1.3x107 (dry)
Clay (Including wet clay) 1 -100
Cobalt 5.6x10-8
Copper 0.0000002 (native) - 1.7x10-8
Drill Mud or Hydraul-EZ 4.5
Fresh Water 10 - 100
Gabbro 103  - 106
Gneiss (various) 6.8x104 (wet) - 3x106 (dry)
Gold 2.4x10-8
Graphite Porphyry 4.5x103 (wet) - 1.3x106 (dry)
Gravel 100 - 10,000
Igneous 100 - 1,000,000
Limestone 100 - 10,000
Marble 102 - 2.5x108 (dry)
Mica 9x102 - 1014
Nickel 7x10-8
Salt Water 0.1 - 1
Sand (Both dry and wet) 1 - 10,000
Sandstone 100 - 10,000
Schist (Calcareous and Mica) 20 - 104
Schist (Graphite) 10 -102
Silver 1.6x10-8
Soil 1 - 10
Tuffs 2x103 (wet) - 105 (dry)

Reference: (Modified, Telford W.M-1990)