Tuffeau stone — in

French French (french: français(e), link=no) may refer to: * Something of, from, or related to France ** French language, which originated in France, and its various dialects and accents ** French people, a nation and ethnic group identified with Franc ...

, simply ''tuffeau'' or ''tufeau'' — is a local

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms w ...

of the Loire Valley of

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

. It is characterized as a chalky or sandy, fine-grained limestone, white to yellowish-cream in appearance, and micaceous (containing some white flakes of

mica Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect basal cleavage. Mica is ...

, or

muscovite Muscovite (also known as common mica, isinglass, or potash mica) is a hydrated phyllosilicate mineral of aluminium and potassium with formula K Al2(Al Si3 O10)( F,O H)2, or ( KF)2( Al2O3)3( SiO2)6( H2O). It has a highly perfect basal cleavag ...

). The soft stone is extracted from numerous quarries and has made a major mark on the architectural landscape of the Loire and its tributaries — especially the valley's world-famous chateaux.

Geology

Tuffeau dates to the

Mesozoic era The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...

(

Upper Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

Turonian The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous Epoch, or a stage in the Upper Cretaceous Series. It spans the time between 93.9 ± 0.8 Ma and 89.8 ± 1 Ma (million years ago). The Turonian is preceded b ...

stage). 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. It differs from genuine

chalk Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. C ...

by the presence of

foraminifera Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly ...

and many remains of shells originally deposited in shallow water (between 2 and 20 meters) and subsequently agitated, near a coastline. In contrast, true chalk is rich in another type of shelly

micro-fossil A microfossil is a fossil that is generally between 0.001 mm and 1 mm in size, the visual study of which requires the use of light or electron microscopy. A fossil which can be studied with the naked eye or low-powered magnification, ...

, the

coccolith Coccoliths are individual plates or scales of calcium carbonate formed by coccolithophores (single-celled phytoplankton such as '' Emiliania huxleyi'') and cover the cell surface arranged in the form of a spherical shell, called a ''coccosphere' ...

, which was deposited in deeper (~ 200 meters), and quieter, water. The term ''tuffeau'' is etymologically related to another stone,

tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock ...

, to which is it not geologically related — and to

tufa Tufa is a variety of limestone formed when carbonate minerals precipitate out of water in unheated rivers or lakes. Geothermally heated hot springs sometimes produce similar (but less porous) carbonate deposits, which are known as travertin ...

, to which it is geologically related. These words derive from Italian ''tufo'' and from Latin ''tōphus'' or ''tōfus'' ("stone").

Physical properties

Tuffeau has a very low density compared with many other rocks, being half as dense as granite, comparable in density with ebony, and only about 10 to 20% heavier than water. It has porosity of up to 50%, whereas that of granite is only about 1%. The compressive strength of the stone is a factor of 10 to 20 times less than that of granite. When mixed with local sand and flinty clays from later eras, tuffeau is said to create the best vineyards soils.

Mining

Carrière de tuffeau à Bourré, Loir-et-Cher

Tuffeau mining reached its peak in the

15th century The 15th century was the century which spans the Julian dates from 1 January 1401 ( MCDI) to 31 December 1500 ( MD). In Europe, the 15th century includes parts of the Late Middle Ages, the Early Renaissance, and the early modern period. ...

. As a construction material — especially in the

Touraine Touraine (; ) is one of the traditional provinces of France. Its capital was Tours. During the political reorganization of French territory in 1790, Touraine was divided between the departments of Indre-et-Loire, :Loir-et-Cher, Indre and Vien ...

and

Anjou Anjou may refer to: Geography and titles France *County of Anjou, a historical county in France and predecessor of the Duchy of Anjou **Count of Anjou, title of nobility *Duchy of Anjou, a historical duchy and later a province of France **Duke ...

regions — tuffeau has been extracted mostly from natural riverside bluffs, which are extensive. The extracted blocks could thus be loaded onto boats. Over the centuries, this has created extensive underground galleries, or mines, some of which are several kilometers in extent. These artificial caves have long been used as human dwellings, as the indoor temperature is remarkably constant from summer to winter. The greatest concentration of these cave dwellers — ''les troglodytes'' — is in the region of

Saumur Saumur () is a commune in the Maine-et-Loire department in western France. The town is located between the Loire and Thouet rivers, and is surrounded by the vineyards of Saumur itself, Chinon, Bourgueil, Coteaux du Layon, etc.. Saumur s ...

The mines are a perfect environment for wine cellars. Many of the larger caves have become '' champignonnieres'' — i.e., are used for growing a commercial variety of mushroom, which is transported daily to the markets of Paris.

Architecture

Numerous buildings in the Loire Valley, from the most modest to the most grandiose, were built from blocks of tuffeau stone, including the Château de Beaulieu near

, the

Château d'Ussé Ussé is a castle 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, ...

and the Château de la Motte d'Usseau, and many worker's cottages at Longères.

Geology

Physical properties

Mining

Architecture

See also