Hank is temporarily disabled and has been collecting rocks to pass the time. Walt Jr. and Hank are both impressed with a pink rock, which Walt goes on to describe why the rock gives it that color. This is a good example of a positive statement, which is a testable statement that has a right or wrong answer. It is not based on some value judgement (like the rock looking cool).
See more: normative analysis, positive analysis
The Economics of Breaking Bad 