Next, let's examine the mineral for any signs of cleavage. Two minerals in this particular group have cleavage (although it is poorly developed). The other does not. The distinction between the two minerals with cleavage is in the angle between the cleavage faces. Without a lot of experience it is a challange to really see that subtle difference.  There are some other hints below to help you decide.  

Two Directions at nearly 90 degrees		Typically will have a "blocky" look and the cleavage faces will not reflect light very well.
Two Directions at 56 degrees and 124 degrees		Typically will have thin elongated structure and the 2 cleavage faces will reflect light  as you rotate the sample around in the light.
No Apparent Cleavage (CLICK HERE)