3. Groundmass
Neither aggregate nor sandy microstructures
 In vughs. No separated aggregates. Groundmass broken by vughs, but not interconnected, 
  with some channels and chambers.
In vughs. No separated aggregates. Groundmass broken by vughs, but not interconnected, 
  with some channels and chambers.
 
 
   In channels. No separated aggregates. Groundmass broken by dominant channels.
In channels. No separated aggregates. Groundmass broken by dominant channels.
 
 
   In chambers. No separated aggregates. Groundmass broken by dominant chambers.
In chambers. No separated aggregates. Groundmass broken by dominant chambers.
 Vesicular. No separated aggregates. Groundmass with dominant vesicles.
Vesicular. No separated aggregates. Groundmass with dominant vesicles.
  Spongy. Few, if any, aggregates. Abundant voids, closely interconnected.
Spongy. Few, if any, aggregates. Abundant voids, closely interconnected.
  Fissured. Few, if any, fully separated 
  aggregates, with many interconnected fissures.
Fissured. Few, if any, fully separated 
  aggregates, with many interconnected fissures.
 
 
    Cracked. No fully separated aggregates, 
  dense material with only a few cracks (and channels).
Cracked. No fully separated aggregates, 
  dense material with only a few cracks (and channels).
 
 
    Massive. No separated aggregates, very 
  dense material, with hardly any voids.
Massive. No separated aggregates, very 
  dense material, with hardly any voids.
 
   
  