Siegfried Siegesmund - Monument Future

The commercial name refers to a wrong petrographic classification: this is a igneous coarse grained rock (amphibole gabbro). Colour: black with some light grey spots. Minerals: plagioclase, hornblende. Decay morphologies: scaling. Geology: “Dioritico – kinzigitica” forma-tion of the “Ivrea-Verbano Zone”. Quarry: near the village of Anzola (val d’Ossola, Verbano province). Use: squared blocks and slabs (Banca Popolare, framework of openings, G. Greppi 1931, Milan); another use was for funerary purposes (Mausoleo Cadorna, M. Piacentini 1932, Pallanza; Cemeteries, Milan).

A stone, of the same colour but unlike origin (migmatite, Gneiss Valcondria), was quarried in val Chiavenna (Sondrio) and used in buildings.

Igneous rock (rhyolitic ignimbrite). Colour: purple to dark red showing clear phenocrysts and some elliptic coarse-grained patches. Minerals: quartz and 43plagioclase. Decay morphologies: scaling. Geology: “Vulcaniti di Auccia” forma-tion (lower Permian). Quarry: near the pass of “Croce Domini” (Bienno, val Camonica – val Trompia, Brescia province). Use: thick slabs for cladding or slabs for flooring (Palazzo delle Colonne, polished thick slabs deeply carved by Giacomo Manzù to represent the “coats of arms” of the Lombard provinces).

Carbonate rock (dolomite). Colour: light pink tending to whitish with fine cracks featuring a typical network. Mineral: dolomite. Decay morphologies: surface erosion with widening of the crack network; sulphate skin formation. Geology: “Dolomia di Zandobbio” formation (Hettangian - Rhaetian) of the sedimentary series of Southern Alps. Quarry: near the villages of Zandobbio (Bergamo proince). Use: firstly during the Renaissance period (i. e. Cappella Colleoni, 1472–76; Biblioteca Angelo Maj, early 17th century); later (20th century) greatly imple-mented (Palazzo Littorio, cladding made of slabs with sawed face, A. Bergonzo 1940, Bergamo) and it was also spread in Milan for residential and public building.

Clastic rock (diamictite with ocraceous matrix and calcite cement, clasts with angular corners). Colour: grey with some yellowish hues. Mineral: clasts of Dolomia principale (Haupt dolomit), size from 0.05 to 1.0 m. Decay morphologies: roughening on clasts and matrix, soot deposition on cavities, sulphate skins formation. Geology: “Complesso di Poltragno”, subdivided in two units (Unità di Poltragno and Unità di Gré), including slope deposits and alluvial deposits (lower and middle Pleistocene). Quarry: near Castro (Bergamo province), on the mountain rising above the north-western shore of lake Iseo. Use: slabs with sawed face for cladding of residential and public buildings (Casa dei Giornalisti, G. Muzio 1936, Milan; Palazzo Vittoria, E. Frisia 1935, Milan). Besides, this conglomerate is employed today (i. e. the façade cladding on the new building of Università Bocconi, Grafton architects 2008, Milan).

Organic carbonate rock (shell limestone, biomicrite – packstone) wiht different varieties according to the colour and the texture (Rosa, Perla, Mandorlato, Paglierino). Colour: white to yellow to pink ground scattered with small light spots (shells of Foraminifera). Mineral: calcite. Decay morphologies: surface erosion, sulphate skin formation. Geology: “Calcari nummulitici” formation (Eocene) of the sedimentary series of the Western Venetia. Quarry: few kilometres near Chiampo, a village of the same valley (Vicenza province); limestone in alternating with basalt. Use: slabs for cladding (Palazzo Popolo d’Italia) or for flooring and stairs (Intendenza di Finanza, Genio Civile 1935, Milan).

Organic carbonate rock (limestone, biosparite-wackestone) with different varieties according to the texture (Fiorito, Granitello). Colour: grey with evidence of shells of Bivalves (Rudistae). Mineral: calcite. Decay morphologies: surface erosion, sulphate skin formation. Geology: “Calcare di Aurisina” formation (upper Creta-ceous) of the Karst of Trieste. Quarry: near Aurisina (Nabrežina) in the north-western part of Karst (Trieste province). Use: early uses are documented in Roman architecture of north-eastern Italy and also in Milan (funerary stelae and blocks of urban walls); nevertheless the stone was used in the 20th century as blocks with point chiseled face (main body of Stazione Centrale, U. Stacchini 1912/31, Milan; former Banca Commerciale now Ragioneria Comunale, L. Beltrami 1913/23, Milan).

Other sedimentary rocks coming from Karst, with similar origin (organic limestone) and composition, were employed in 20th century architecture for flooring and cladding: Gabria Tomadio, Lipos, Repen.

Organic carbonate rock (shell limestone; bio-sparite / packstone). Colour: pinkish to yellowish with some variegations with evidence of shells of Bivalves (Chlamys). Mineral: calcite. Decay morphologies: surface erosion; sulphate skin formation. Geology: “Calcare di Finale Ligure” formation (lower 44Miocene) of post-orogenetic deposits of the “Bacino del Finalese”. Quarry: near Orco-Feglino, few kilometres north of Finale Ligure (Savona). Use: thick point chiseled slabs mainly employed for cladding (Università L. Bocconi, G. Pagano 1941, Milan; Palazzo del Toro, E. Lancia 1939, Milan).

Nodular carbonate rock with ammonite shells (limestone, biomicrite). Colour: dark red with white veins and pink shades. Minerals: calcite, haematite. Decay morphologies: surface erosion, sulphate skin formation, chromatic alteration. Geology: “Calcare ammonitifero” formation (lower Lias) of the non-metamorphic series of Tuscany. Quarry: south of Roccalbegna (Grosseto province). Use: polished slabs mainly for flooring in residential and public buildings (Casa Wassermann, a four-storeys urban residence with an accurate choice of coloured stones for flooring, P. Portaluppi 1934, Milan).

Carbonate rock (pseudo-breccia, limestone). Colour: red to purple with white, purple or pink irregular spots and very thin grey or purple veins. Mineral: calcite. Decay morphologies: surface erosion, sulphate skin formation, chromatic alte-ration. Geology: “Calcare mas-siccio” formation (Hettangian, lower Lias) of the non-metamorphic series of Tuscany. Quarry: Caldana (south of Gavorrano, Grosseto province). Use: polished slabs mainly for flooring in residential buildings together with other coloured marbles, Casa Wassermann). A significant use is displayed on the great staircases of Milan’s Stazione Centrale (U. Stacchini 1912/31): the big shafts are made assembling moulded pieces of curvilinear shape and pieces of fluted shape.

Carbonate stone with spongy appearance. Colour: creamy-white or yellowish; Mineral: calcite. Decay morphologies: roughening, sulphate skin formation, soot deposits in the cavities. Geology: carbonate deposition from hot springs (Upper Pleistocene). Quarry: near Serre di Rapolano, east of Sienna (Tuscany). Use: the stone was taken in great consideration during the Thirties as blocks and thick slabs with sawed face for cladding (Main Atrium of the Stazione Centrale; Ca’ Brütta, lower part of façades, G. Muzio 1922; Palazzo della Borsa, colonnaded façade, P. Mezzanotte 1932, Milan). This stone is very similar to Travertino romano ( Lapis Tiburtinus , coming from Tivoli-Guidonia, Rome), largely used in ancient Rome and by Baroque architects, later (since the third decade of 20th century) spread in the whole Italian territory.