diff --git a/MaterialLib/FractureModels/LinearElasticIsotropic.h b/MaterialLib/FractureModels/LinearElasticIsotropic.h
index a005fea2708c21a544de193166b38eb7845f734b..76a1596bb70706e72424c009797a1404de358e9b 100644
--- a/MaterialLib/FractureModels/LinearElasticIsotropic.h
+++ b/MaterialLib/FractureModels/LinearElasticIsotropic.h
@@ -36,7 +36,9 @@ public:
         {
         }
 
+        /// Normal stiffness given in units of stress.
         P const& normal_stiffness;
+        /// Shear stiffness given in units of stress.
         P const& shear_stiffness;
     };
 
diff --git a/MaterialLib/FractureModels/MohrCoulomb.h b/MaterialLib/FractureModels/MohrCoulomb.h
index 82b599bbb8c6e6ca926692480a4135a58795124f..c2b4792e97037b4d01392aa3313717f1cdc4f972 100644
--- a/MaterialLib/FractureModels/MohrCoulomb.h
+++ b/MaterialLib/FractureModels/MohrCoulomb.h
@@ -41,10 +41,18 @@ public:
         {
         }
 
+        /// Normal stiffness given in units of stress.
         P const& normal_stiffness;
+        /// Shear stiffness given in units of stress.
         P const& shear_stiffness;
+        /// Governs the normal stress dependence of the shear strength.
+        /// \note Given in degrees (not radian).
         P const& friction_angle;
+        /// Governs the dilatancy behaviour during the plastic deformation of
+        /// the fault.
+        /// \note Given in degrees (not radian).
         P const& dilatancy_angle;
+        /// Fracture cohesion in units of stress.
         P const& cohesion;
     };
 
@@ -108,12 +116,14 @@ public:
             material_state_variables) override;
 
 private:
-    /// \copydoc
-    /// MaterialLib::Fracture::LinearElasticIsotropic::_penalty_aperture_cutoff
+    /// Compressive normal displacements above this value will not enter the
+    /// computation of the normal stiffness modulus of the fracture.
+    /// \note Setting this to the initial aperture value allows negative
+    /// apertures.
     double const _penalty_aperture_cutoff;
 
-    /// \copydoc
-    /// MaterialLib::Fracture::LinearElasticIsotropic::_tension_cutoff
+    /// If set no resistance to open the fracture over the initial aperture is
+    /// opposed.
     bool const _tension_cutoff;
 
     MaterialProperties _mp;