Monti della Tolfa

The Monti della Tolfa (or Tolfa Mountains) are a

volcanic group A volcanic group is a stratigraphic group consisting of volcanic strata. They can be in the form of volcanic fields, volcanic complexes and cone A cone is a three-dimensional geometric shape that tapers smoothly from a flat base (frequ ...

in the Anti-Apennines of the northern part of the

Lazio it, Laziale , population_note = , population_blank1_title = , population_blank1 = , demographics_type1 = , demographics1_footnotes = , demographics1_title1 = , demographics1_info1 = , demographics1_title2 ...

region of

Central Italy Central Italy ( it, Italia centrale or just ) is one of the five official statistical regions of Italy used by the National Institute of Statistics (ISTAT), a first-level NUTS region, and a European Parliament constituency. Regions Central I ...

. They are bounded by the

Tyrrhenian Sea The Tyrrhenian Sea (; it, Mar Tirreno , french: Mer Tyrrhénienne , sc, Mare Tirrenu, co, Mari Tirrenu, scn, Mari Tirrenu, nap, Mare Tirreno) is part of the Mediterranean Sea off the western coast of Italy. It is named for the Tyrrhenian pe ...

coast to the west, by the

Monti Sabatini The Monti Sabatini is a geologic region in Lazio, central Italy, a remnant of intense volcanism which started ca. 600,000 years ago, mainly with pyroclastic and maar forming eruptions which continued until 100,000 years ago. The moun ...

to the east, and by the Monti Cimini and the Mignone river to the north.

Tolfa Tolfa is a town and '' comune'' of the Metropolitan City of Rome, in the Lazio region of central Italy; it lies to the ENE of Civitavecchia by road. It is the main center in the Monti della Tolfa, an extinct volcanic group between Civitavecchia ...

and

Allumiere Allumiere ( Romanesco: ) is a '' comune'' (municipality) in the Metropolitan City of Rome in the Italian region Latium, located about northwest of Rome. Allumiere is traditionally divided into the ''contrade'' of Burò, Ghetto, La Bianca, Nona, P ...

are the principal towns. The highest peak is the Monte Maggiore (633 m above sea level). The Monti della Tolfa consists mostly of

trachyte Trachyte () is an extrusive igneous rock composed mostly of alkali feldspar. It is usually light-colored and aphanitic (fine-grained), with minor amounts of mafic minerals, and is formed by the rapid cooling of lava enriched with silica and al ...

s formed during the

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', ...

and the early

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

. The mountains are an important source of

alunite Alunite is a hydroxylated aluminium potassium sulfate mineral, formula K Al3( S O4)2(O H)6. It was first observed in the 15th century at Tolfa, near Rome, where it was mined for the manufacture of alum. First called ''aluminilite'' by J.C. D ...

, from which

alum An alum () is a type of chemical compound, usually a hydrated double sulfate salt of aluminium with the general formula , where is a monovalent cation such as potassium or ammonium. By itself, "alum" often refers to potassium alum, with the ...

is extracted. The mineral was discovered there in 1461, and extensively mined until the mine closed in 1941, after almost 500 years; for much of this time it was the principal source of alum in Europe. The Tolfetano breed of horse originates in the area, and takes its name from it. {{DEFAULTSORT:Tolfa Mountain ranges of the Apennines Mountain ranges of Italy Mountains of Lazio Volcanic groups Latial culture