[cpdiii]

Is the stone pumice which is easily cut and worked??

[cogitator]

It's not pumice; it's an impact breccia (a mineral formed by the fusion of hot semi-molten rock formed after the impact). The mineral is called "suevite". I don't know about its properties, but I expect that it's easily worked (and it's also fairly easily erodable, because they've had to replace several of the blocks in the church edifice because of excessive weathering).