Syntaxial Overgrowth

A syntaxial growth is a crystallographically oriented overgrowth of a mineral on a substrate of the same chemical composition. Syntaxial overgrowths are common in cements in sedimentary rocks including quartz overgrowth cements and calcite syntaxial cements and syntaxial rims. In carbonate rocks syntaxial rims are common around echinoid bioclasts since these often consist of a single calcite crystals. Syntaxial overgrowth in igneous rocks occurs in cumulates by secondary growth. Where the overgrowth mineral is different from the underlying substrate it is known as epitaxial growth.

Bibliography

• E. WM. Heinrich (1956): Microscopic Petrografy. Mcgraw-hill book company,inc
• M. J. Hibbard (1994): Petrography to Petrogenesis. Prentice Hall editore

Photo
Crinoid fragment with calcite syntaxial overgrowth. Immagine a NX, 10x (lato lungo = 2mm)	Crinoid fragment with calcite syntaxial overgrowth. Immagine a NX, 10x (lato lungo = 2mm)	Crinoid fragment with calcite syntaxial overgrowth. Immagine a NX, 10x (lato lungo = 2mm)
Crinoid fragment with calcite syntaxial overgrowth. Immagine a NX, 10x (lato lungo = 2mm)	Crinoid fragment with calcite syntaxial overgrowth. Immagine a NX, 10x (lato lungo = 2mm)	Crinoid fragment with calcite syntaxial overgrowth. Immagine a NX, 10x (lato lungo = 2mm)