Two varieties of "bluestone" can be found on the streets of Amsterdam's city centre. Large blocks and slabs of this stone that have been traditionally used in the oldest buildings of the city have been quarried in The Ardennes, Belgium. This Carboniferous limestone is very rich in fossil remains of some of some the main marine groups of that period, such as crinoids (sea lilies) and brachiopods. Crinoid fragments are very common in Belgium "bluestone", as can be seen in many buildings of Amsterdam' city centre.

Over the last few decades, the city of Amsterdam has renewed the paving stones of many cities with Irish "bluestone". Although the Irish "bluestone" is about ten million years younger that the Belgium "bluestone", it was formed in the same shallow, tropical sea, therefore they share many features. The fossil content of the Irish "bluestone" is very similar to the older Belgium limestone, although the former usually preserves a larger proportion of brachiopods and corals. One of the most characteristic features of the Irish "bluestone" is the ubiquitous presence of Productive brachiopods. These marine shells are relatively large, some of them more than 10 cm long.

Irish "bluestone" with Productida brachiopods



Irish "bluestone" with Productida brachiopods


Longitudinal cross section of a gastropod in a "bluestone"