EDITORIAL TRANSPARENCY
The sources.
The method. The limitations.
These guides distinguish what the catalogue states about products from general information about stone families.
How the comparison was prepared
The Brazilian quartzite and river pebble product details were checked on 17 October 2026; the other details on 16 October 2026. The commercial references are the Pietrarredo product listings linked on the material pages.
Data from one manufacturer or quarry does not certify a supply from another seller. We have not assigned undocumented Mohs ratings, percentages, laboratory results or certifications to Pietrarredo products.
Test standards are cited as references for reading technical data, rather than as a declaration of product conformity. For a detailed design, request documentation for the selection purchased and review it with your technical adviser or installer.
Technical references
Further reading from universities, research institutes and public technical services on stone materials and test methods. Results relate to the samples studied and do not certify the performance of individual Pietrarredo supplies.
- Politecnico di Torino · Natural Stone Testing (new tab)
The university’s Raw Materials Research Group lists methods for assessing abrasion, bending, frost, absorption and slip resistance in natural stone.
- Regione Piemonte · Petrographic and Technical Data Sheets (PDF) (new tab)
A regional document with Grey Beola and Luserna Stone data sheets on pages 40 and 81: composition and physical and mechanical properties of the materials examined.
- Autonomous Province of Trento · Forte Buso Porphyry (new tab)
A Geological Service data sheet with petrographic analysis and absorption, abrasion, bending and frost tests on porphyry samples.
- CNR · Study of Trani Stone Properties (new tab)
A study by A. Calia, L. Matera and M. Lettieri on the characterisation of Trani stone and its response to water. The page provides the citation and abstract.
- CNR–IGG · Cultural Heritage Laboratory (new tab)
Methods for characterising stone surfaces and research on absorption, porosity, deterioration, cleaning and stone protection.
- Smithsonian National Museum of Natural History – Metamorphic Rock Quartzite (new tab)
Explains quartzite’s formation and its structure of interlocking quartz crystals. Information about the geological family, rather than a test of Pietrarredo products.
- ISPRA, CARG Project – Explanatory Notes to Sheet 279 Urbino (new tab)
Its description of alluvial sequences documents rounded pebbles of mixed rock types. A general geological reference, without assigning a specific composition to the Ticino pebbles sold by Pietrarredo.
Official product details for the eight options
- Porphyry (new tab)
- Grey Beola (new tab)
- Luserna Stone (new tab)
- Sandstone (new tab)
- Green Serpentine (new tab)
- Trani Stone · Antiqua (new tab)
- Brazilian Quartzite (new tab)
- River Pebbles (new tab)
The photographs
The images come from the Pietrarredo photo archive supplied for this project. Original versions without a logo were selected and optimised for the web. The photographs illustrate a family of stones and do not constitute a contractual sample of a specific supply.