Stay-at-Home Day Five, Monday 30 March 2020: Stone Five

Stone One

Stone Two.

Stone Three.

Stone Four.

Above are the first four stones already presented in this Series. The first Post is Stay-at-Home Day One.

Stone Five, from Gemstone Beach, appears at first sight to be a white stone with streaks of brown throughout:

However, closer inspection reveals that this is composed, like Stone One, of many small fragments held together in a fine-grained matrix:

Close-up of Stone Five from Gemstone Beach.

Close-up of Stone Five from Gemstone Beach.

Close-up of Stone Five from Gemstone Beach.

Stone Five.

The fragments look like quartz. This stone would be a “breccia” if the fragments were angular but would be a “conglomerate” if they were rounded due to abrasion from the actions of water or wind. Breccias form close to the site where the constituent fragments have been created, while conglomerates form further away, after the fragments have travelled somewhat and had their angular edges rounded off. It seems to me that most of the fragments are angular with only the occasional one showing some abrasion. This leads me to identify it as an example of a breccia. 

The next Post in this Series is Stay-at-Home Day Six.

Author: tumblestoneblog

Retired Academic, male, living in the New Zealand countryside near Whanganui with his wife as well as Jasper the dog, Fluffy the cat, Dancer and Penny, the horses, and a shed half-full of stones. Email john.tumblestone@gmail.com. View all posts by tumblestoneblog