Current version of topical coding scheme for igneous rocks (as of 11/8)

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Topical Code Subcategory Indices Topical Hierarchy (from Ned, Sue & Scott)
First Number Number of Specimens Last Number Top Level Second Level Third Level Third Level
        I. Plutonic Structures      
ICs 1 10 10   A. Crystallization Structures - unclassified    
  11 20 30     1. Bedding, Graded bedding  
  31 20 50     2. Orbicular  
  51 20 70     3. Miarolitic cavities  
IIs 1 5 5   B. Intrusive Structures - unclassified    
  6 10 15     1. Chilled margin  
  16 10 25     2. Veins  
  26 10 35     3. Xenoliths  
  36 10 45     4. Magma Mixing Structures  
  46 10 55     5. Intrusive feature (apophyse)  
  56 10 65     6. Intrusive breccia  
IPt 1 5 5 II. Plutonic Textures - unclassified      
  6 10 15   A. Porphyritic    
  16 10 25   B. Poikilitic    
  26 10 35   C. Magmatic foliation and lineation    
  36 10 45   D. Cumulate    
  46 10 55   E. Graphic    
  56 10 65   F. Pegmatitic/aplitic    
        III. Plutonic Rock Types      
          A. Granitoid Lithologies    
IGr 1 100 100     1. Granite  
IGd 1 100 100     2. Granodiorite  
ITo 1 100 100     3. Tonalite  
ISy 1 50 50     4. Syenite  
  51 50 100       a. Quartz Syenite
IMz 1 50 50     5. Monzonite  
  51 50 100       a. Quartz Monzonite
IDi 1 50 50     6. Diorite  
  51 50 100       a. Quartz Diorite
IPm 1 30 30   B. Mafic Lithologies - unclassified    
  31 40 70     1. Gabbro  
  71 15 85     2. Anorthosite  
IPu 1 5 5   C. Ultramafic Lithologies - unclassified    
  6 10 15     1. Dunite  
  16 10 25     2. Harzburgite  
  26 10 35     3. Lherzolite  
  36 10 45     4. Wehrlite  
  46 10 55     5. Pyroxenite  
  56 10 65     6. Hornblendite  
IPn 1 100 100   D. Feldspathoid-bearing Lithologies    
        IV. Volcanic Structures      
IVe 1 10 10   A. Ejecta - unclassified    
  11 15 25     1. Bombs and Blocks  
  26 15 40     2. Spatter  
  41 15 55     3. Lapilli  
  56 15 70     4. Ash  
IVl 1 10 10   B. Lava Structures - unclassified    
  11 15 25     1. Pillows  
  26 15 40     2. Pahoehoe  
  41 15 55     3. Aa  
  56 15 70     4. Columnar jointing  
  71 15 85     5. Flow banding  
IVv 1 10 10   C. Vesicular Structures - unclassified    
  11 15 25     1. Scoriaceous  
  26 15 40     2. Pumiceous  
  41 15 55     3. Amygdaloidal  
IXe 1 100 100   D. Xenoliths    
IMm 1 100 100   E. Magma Mixing Structures    
IVa 1 100 100 V. Volcanic Alteration Features - unclassified      
IVh 1 10 10   A. Hydration - unclassified    
  11 20 30     1. Perlitic  
  31 20 50     2. Apache’s tears  
IVd 1 10 10   B. Devitrification - unclassified    
  11 20 30     1. Spherulitic  
IVt 1 5 5 VI. Volcanic Textures - unclassified      
  6 10 15   A. Holohyaline (glassy, vitrophyric)    
  16 10 25   B. Porphyritic    
  26 10 35   C. Diabasic    
  36 10 45   D. Trachytic    
  46 10 55   E. Poikilitic    
  56 10 65   F. Resorption/Reaction    
  66 10 75   G. Mineral Zoning?????? (remove this?)    
        VII. Volcanic Rock Types      
IVf 1 25 25   A. Felsic Volcanic Lithologies - unclassified    
  26 15 40     1. Rhyolite  
  41 15 55     2. Obsidian  
  56 15 70     3. Dacite  
  71 15 85     4. Latite  
  86 15 100     5. Trachyte  
IVi 1 30 30   B. Intermediate Volcanic Lithologies - unclassified    
  31 20 50     1. Andesite  
IVm 1 15 15   C. Mafic Volcanic Lithologies - unclassified    
  16 10 25     1. Basalts - unclassified  
  26 10 35       a. ocean island basalts
  36 10 45       b. mid-ocean ridge basalts
  46 10 55       c. island arc basalts
  56 10 65       d. continental arc basalts
  66 10 75       e. flood basalts
  76 10 85       f. continental rift basalts
  86 15 100     2. Basalt Glass (Tachylite)  
IVn 1 100 100   D. Feldspathoidal Volcanic Lithologies    
IPy 1 10 10   E. Pyroclastic rocks - unclassified    
  11 10 20     1. Tuff - unclassified  
  21 15 35       a. welded tuff
  36 15 50       b. non-welded tuff
  51 20 70     2. Breccia