Hand Specimen
This rock is made up of well cemented bioclasts. The bioclasts (mainly shell fragments) are poorly sorted, ranging from <1mm up to a few 10s of mm.
Fine-grained cement fizzes with acid, indicating that it is carbonate. It has weathered to a pale yellow-grey.
Thin-section
Carbonate fossil fragment in a carbonate cement (sparite). The laminated structure of the shells is visible in places.
Cement contains some hematite (brown regions).
There are a few epidote grains and some opaque areas.
This is a rudstone (Dunham naming system) or biosparite (Folk naming system).
Rock History
The shells are not in life position – they have been transported.
Deposited in moderate to high energy environment.
Rock Name
shelly limestone