mortar structure

Porphyroclast surrounded by an finegrained aggregate of the same mineral. Mortar structure is similar to core-and-mantle structure but the new grains are smaller. A mortar structure is not necessarily formed by recrystallisation, but possibly by cataclasis or a combination of both. The use of this term is discouraged because of its (commonly erroneous) genetic implication of “mechanically crushed rock”

Related terms:

• fracture cleavage
• flaser structure
• atoll structure
• Mineral Structure
• collapse structure
• primary structure
• imbricate structure
• window structure
• book structure
• secondary structure