Achille De Zigno weaved an international network of scientific relationships, witnessed by a dense epistolary of 170 correspondents, among which are scholars from Padua like Molin, Omboni and De Visiani, and famous scientists like Capellini, Cocchi, Hall, Krantz, Murchison, Pilla, Scarabelli, Tavanelli, Unger and Zittel.

In those letters we can read about various scientific debates, exchange of publications and of palaeontological collections.

In a letter dated June 19th, 1844, Leopoldo Pilla (1805 -1848), planning an excursion in the area of Vicenza, asked De Zigno to give him some advice about what to read on the sedimentary succession of Recoaro, and about the most interesting places to visit. Also, Pilla asked De Zigno to join him, if he could.

Both geologists had been together on an excursion on the Euganean Hills in September 1842, witnessed by autographed annotations by Pilla himself on one of the De Zigno field notebooks. Among those annotations there is a sketch of the view from the balcony of Petrarca’s home in Arquà.

In a letter dated March 30th, 1855, referring to the studies carried out by De Zigno on the Jurassic flora in Veneto, the famous French palaeobotanist Alexandre Brongniart (1770 – 1847) wrote to him about similar fossil plants that were found in other European sites.