1. powder M2A2S5 µ-cordierite 10 -3 -10 -1 30-3 Müller et al . (1995)
2. ground M2A2S5 µ-cordierite 0.2-7 ×10 -2 22-4 Müller & Thamm (1990)
3. CZA 2 S willemite 3 ×10 -2 6 McMillan (1982)
4. mechanically M2A2S5 µ-cordierite 1-10 ×10 -4 100-30 Müller & Thamm (1990)
5. polished 2 ×10 -4 70 Yuritsyn et al . (1994a)