Tuffeau stone
Encyclopedia
Tuffeau is a marine sedimentary rock
which is found in the Loire Valley
of France
.
The Loire Valley formed the floor of a vast sea 90 million years ago. Over the millennia, sediment from the sea floor, comprising fossilized living organisms and sand particles, became compressed to form what is now known as Tuffeau stone.
Mining of Tuffeau stone for construction reached its peak in the 15th century, and the mining techniques used to extract the valued stone created a vast network of troglodyte or troglodytic caves in the Loire Valley, France, through which flows the great Loire River. The caves have been used as dwellings in the past, partly due to the practicality that the indoor temperature is remarkably constant from summer to winter.
Today, many of the larger caves are used for growing a wide variety of mushrooms, which are transported daily to the markets in Paris. The Loire is the largest supplier of mushrooms to Paris.
Today, a number of older dwellings, from the magnificent Château d'Ussé
and Château de la Motte d'Usseau to the many modest worker's cottages (Longères), are still standing having been built from large blocks of this wonderful material. A particularly beautiful building constructed of tuffeau is the Château de Beaulieu which stands on the banks of the Loire River just outside the town of Saumur
.
Tuffeau has a very low density compared with many other rocks; for example, it is about half as dense as granite and, indeed, is only about 10 to 20% heavier than water. In fact, ebony wood is almost as dense as tuffeau stone! Also, tuffeau has an amazing porosity of up to 50%, whereas that of granite is only about 1%. The porosity of tuffeau can easily be demonstrated by projecting water onto a tuffeau wall (by hose or other means) and observing its immediate absorption by the wall; with granite, there would be, of course, clear 'splash back'. Given tuffeau's porosity it is not surprising that the compressive strength of the stone is a factor of ten to twenty times less than that of granite.
It's a beautiful, but fragile, stone.
Rock (geology)
In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
which is found in the Loire Valley
Loire Valley
The Loire Valley , spanning , is located in the middle stretch of the Loire River in central France. Its area comprises approximately . It is referred to as the Cradle of the French Language, and the Garden of France due to the abundance of vineyards, fruit orchards, and artichoke, asparagus, and...
of France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
.
Mining of Tuffeau stone for construction reached its peak in the 15th century, and the mining techniques used to extract the valued stone created a vast network of troglodyte or troglodytic caves in the Loire Valley, France, through which flows the great Loire River. The caves have been used as dwellings in the past, partly due to the practicality that the indoor temperature is remarkably constant from summer to winter.
Today, a number of older dwellings, from the magnificent Château d'Ussé
Château d'Ussé
The Château d'Ussé is located in the commune of Rigny-Ussé in the Indre-et-Loire département, in France. The stronghold at the edge of the Chinon forest overlooking the Indre Valley was first fortified in the eleventh century by the Norman seigneur of Ussé, Gueldin de Saumur, who surrounded the...
and Château de la Motte d'Usseau to the many modest worker's cottages (Longères), are still standing having been built from large blocks of this wonderful material. A particularly beautiful building constructed of tuffeau is the Château de Beaulieu which stands on the banks of the Loire River just outside the town of Saumur
Saumur
Saumur is a commune in the Maine-et-Loire department in western France.The historic town is located between the Loire and Thouet rivers, and is surrounded by the vineyards of Saumur itself, Chinon, Bourgueil, Coteaux du Layon, etc...
.
Tuffeau has a very low density compared with many other rocks; for example, it is about half as dense as granite and, indeed, is only about 10 to 20% heavier than water. In fact, ebony wood is almost as dense as tuffeau stone! Also, tuffeau has an amazing porosity of up to 50%, whereas that of granite is only about 1%. The porosity of tuffeau can easily be demonstrated by projecting water onto a tuffeau wall (by hose or other means) and observing its immediate absorption by the wall; with granite, there would be, of course, clear 'splash back'. Given tuffeau's porosity it is not surprising that the compressive strength of the stone is a factor of ten to twenty times less than that of granite.
It's a beautiful, but fragile, stone.