Colonnata Black Limestone

Generale_Calcare Nero di Colonnata
Detail of the churchyard (Santissima Annunziata) in Colonnata Black Limestone.

Lithotype

Colonnata Black Limestone

Common names

Nero di Colonnata

Rock classification

Sedimentary rock

The outcrops of this rock are present in different areas of Carrara province; however, the main outcrops of this black and grayish limestones occur along the western slope of the Cima d’Uomo and Monte Bandita and near the Carpenetella, Tacca and Canaloni quarries, along the homonymous canal close to the Colonnata village (Carrara).

Fine-grained black limestone in the process of initial crystallization. Geometrically, it represents the higher part of the sequence of crystalline dolomites of the Grezzoni Formation. The age of the formation is final Trias Retico and Infralias (rocks of uncertain age between the Triassic and Lower Giurassic).

In Firenze it was used mainly in the churchyard and in the decorations of the Basilica della Santissima Annunziata and in the interior pavement of the Cattedrale di Santa Maria del Fiore.

The composition is mainly calcitic (>90%) with low amount of dolomite and clay minerals.

Macroscopic description

Fine-grained black limestone; the presence of small amount of dolomite, the very fine grained and compact texture make it a rather tough material to cut.

Hand sample of a Colonnata Black Limestone.

Microscopic description

Calcareous biomycrite classified as a wackestone. Microfossils and calcitic veins are observable.

Thin section micrograph of a Colonnata Black Limestone.