diff --git a/rtchallenge/src/materials.rs b/rtchallenge/src/materials.rs
index 8446795..e963d86 100644
--- a/rtchallenge/src/materials.rs
+++ b/rtchallenge/src/materials.rs
@@ -18,6 +18,8 @@ pub struct Material {
     pub specular: Float,
     pub shininess: Float,
     pub reflective: Float,
+    pub transparency: Float,
+    pub refractive_index: Float,
 }
 
 impl Default for Material {
@@ -37,6 +39,8 @@ impl Default for Material {
     ///         specular: 0.9,
     ///         shininess: 200.,
     ///         reflective: 0.0,
+    ///         transparency: 0.0,
+    ///         refractive_index: 1.0,
     ///     }
     /// );
     /// ```
@@ -48,6 +52,8 @@ impl Default for Material {
             specular: 0.9,
             shininess: 200.,
             reflective: 0.0,
+            transparency: 0.0,
+            refractive_index: 1.0,
         }
     }
 }