This hard limestone is durable and the fossil inclusions make it very desirable.

The church was built from very hard limestone without an architect or contractor.

The ballmill allows grinding of the harder limestones that are more common than chalk.

A fine High Gothic chapter house was built of best quality hard limestone.

Made of hard, blackish limestone, it is 10 feet high and a little wider.

Depending on the area, the building material used could be either hard limestone or calcareous tufa.

The species is preserved without flattening in a hard limestone, which fills the interior of the specimen.

The streams of soft volcanic debris eroded faster than the hard limestone.

Although the hard limestone could be pierced, water flooded the tunnel and continually threatened to drown the workers.

There was also a hard platform composed of hard limestone and plaster built within the housing structure area.