diff --git a/openmc/element.py b/openmc/element.py
index 94b6ae8d6d..3df2ff1f24 100644
--- a/openmc/element.py
+++ b/openmc/element.py
@@ -62,7 +62,7 @@ class Element(str):
             Single nuclide name to enrich from a natural composition (e.g., 'O16')
         enrichment_type: {'ao', 'wo'}, optional
             'ao' for enrichment as atom percent and 'wo' for weight percent.
-            Default is 'ao'
+            Default is: 'ao' for two-isotope enrichment; 'wo' for U enrichment
         cross_sections : str, optional
             Location of cross_sections.xml file. Default is None.
 
@@ -103,7 +103,7 @@ class Element(str):
         When the `enrichment` argument is specified with `enrichment_target`, a
         general enrichment procedure is used for elements composed of exactly
         two naturally-occurring isotopes. `enrichment` is interpreted as atom
-        percent by default but can be controlled by the `enrichment_type` 
+        percent by default but can be controlled by the `enrichment_type`
         argument.
 
         """
diff --git a/openmc/material.py b/openmc/material.py
index e9ef21db06..fd9f92113c 100644
--- a/openmc/material.py
+++ b/openmc/material.py
@@ -522,7 +522,7 @@ class Material(IDManagerMixin):
             Single nuclide name to enrich from a natural composition (e.g., 'O16')
         enrichment_type: {'ao', 'wo'}, optional
             'ao' for enrichment as atom percent and 'wo' for weight percent.
-            Default is 'ao'
+            Default is: 'ao' for two-isotope enrichment; 'wo' for U enrichment
 
         Notes
         -----
diff --git a/tests/unit_tests/test_element.py b/tests/unit_tests/test_element.py
index ebbdab24e8..bacb988b9a 100644
--- a/tests/unit_tests/test_element.py
+++ b/tests/unit_tests/test_element.py
@@ -3,9 +3,6 @@ from pytest import approx, raises
 
 from openmc.data import NATURAL_ABUNDANCE, atomic_mass
 
-# Relative tolerance for float comparison
-TOL = 1e-9
-
 
 def test_expand_no_enrichment():
     """ Expand Li in natural compositions"""
@@ -13,7 +10,7 @@ def test_expand_no_enrichment():
 
     # Verify the expansion into ATOMIC fraction against natural composition
     for isotope in lithium.expand(100.0, 'ao'):
-        assert isotope[1] == approx(NATURAL_ABUNDANCE[isotope[0]] * 100.0, rel=TOL)
+        assert isotope[1] == approx(NATURAL_ABUNDANCE[isotope[0]] * 100.0)
 
     # Verify the expansion into WEIGHT fraction against natural composition
     natural = {'Li6': NATURAL_ABUNDANCE['Li6'] * atomic_mass('Li6'),
@@ -23,7 +20,7 @@ def test_expand_no_enrichment():
         natural[key] /= li_am
 
     for isotope in lithium.expand(100.0, 'wo'):
-        assert isotope[1] == approx(natural[isotope[0]] * 100.0, rel=TOL)
+        assert isotope[1] == approx(natural[isotope[0]] * 100.0)
 
 
 def test_expand_enrichment():
@@ -33,11 +30,11 @@ def test_expand_enrichment():
     # Verify the enrichment by atoms
     ref = {'Li6': 75.0, 'Li7': 25.0}
     for isotope in lithium.expand(100.0, 'ao', 25.0, 'Li7', 'ao'):
-        assert isotope[1] == approx(ref[isotope[0]], rel=TOL)
+        assert isotope[1] == approx(ref[isotope[0]])
 
     # Verify the enrichment by weight
     for isotope in lithium.expand(100.0, 'wo', 25.0, 'Li7', 'wo'):
-        assert isotope[1] == approx(ref[isotope[0]], rel=TOL)
+        assert isotope[1] == approx(ref[isotope[0]])
 
 
 def test_expand_exceptions():