Stable Mineral Assemblages of Igneous Rocks

1. Front Matter

   Pages n1-XIV

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2. Introduction

   • Alfred Rittmann

   Pages 1-13

3. Igneous Rock Facies

   • Alfred Rittmann

   Pages 14-21

4. Basic Principles of the Calculation

   • Alfred Rittmann

   Pages 22-34

5. Igneous Rock Forming Minerals

   • Alfred Rittmann

   Pages 35-59

6. Use of the Key Tables

   • Alfred Rittmann

   Pages 60-69

7. Heteromorphism and Systematics

   • Alfred Rittmann

   Pages 70-73

8. Comparison between the Stable Mineral Assemblage and the Mode

   • Alfred Rittmann

   Pages 74-87

9. Keys for Calculation

   • Alfred Rittmann

   Pages 88-139

10. Examples

    • Alfred Rittmann

    Pages 140-181

11. Appendix

    • Alfred Rittmann

    Pages 182-204

12. Comparison of the C.I.P.W. Norm with the Rittmann Norm

    • Violetta Gottini

    Pages 205-215

13. ALGOL Program for the Computation of the Rittmann Norm

    • Wolfgang Hewers, Rudolf Stengelin

    Pages 217-223

14. Application of the Rittmann Norm Method to Petrological Problems

    • Hans Pichler, Rudolf Stengelin

    Pages 225-247

15. Back Matter

    Pages 249-264

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This book represents the results of a lengthy study which Professor ALFRED RITTMANN began some thirty years ago. The relationship between the chemical and mineralogical composition of igneous rocks is established as far as is possible. Petrographers will appreciate that this problem is extremely complex, particularly since this relationship forms the basis of the classification and nomenclature of igneous rocks. The ingenious scheme of calculation of the CI.P.W. norm system is essentially chemical in nature. The compositions of the stoichiometrically ideal "normative minerals" do not correspond to those of the constituent minerals found in rocks. Although the "norm" is not intended to equal the "mode" or actual mineral composition of a rock, at least a qualitative agreement between the norm and the mode is desirable. For a number of rocks and rock groups, especially the leucocratic and silicic rocks, the deviation of the norm from the mode is generally within tolerable limits. For the melanocratic and highly subsilicic rocks, on the other hand, the CI.P. W. scheme of calculation too often yields results which fail to reflect the observed mineral composition. The anomalies produced in the cal­ culation of extremely subsilicic volcanic rocks have recently been briefly discussed by F. CHAVES and H. S. YODER, JR. (1971).

• Gestein
• Vulkangestein
• classification
• evolution
• igneous rock
• mineral
• petrography
• volcanic rock

• Istituto Internazionale di Vulcanologia, Catania, Italy

  Alfred Rittmann

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