Usually, nanostructures have an artificial origin, indeed they are fabricated by top-down (e.g., ball milling, laser ablation in liquids, sputtering, etc.) or bottom-up (i.e., chemical synthesis) approaches. However, nanostructures are occasionally available also in nature. The clinoptilolite mineral is the most relevant example of a nanostructured material made by nature. Clinoptilolite is a very common type of natural zeolite, widely available on the market at low cost. Zeolites are silicoaluminate compounds, containing charge-balancing cations of alkali (Na⁺, K⁺) and alkaline-heart (Ca²⁺, Mg²⁺) metals. Owing to their microporous structure, these substances are technologically very useful; indeed, zeolites have cavities (cages) in the crystalline lattice, that are connected together to form a regular array of channels. Clinoptilolite has a finely-grained texture made of lamellar crystals with a thickness of 40nm and containing a two-dimensional array of channels placed in parallel with the lamellar basal planes. These lamellas are compactly staked together, leading to a structure resembling the ‘Opus Latericium’ used in the ancient Roman architecture. This highly robust microstructure allows the clinoptilolite mineral to exhibit good mechanical properties and mesoporosity (inter-lamellar porosity), in addition to the typical microporosity (molecularly-sized porosity), which characterizes all zeolite types ^[1]. To observe the nano-sized texture of clinoptilolite, made of identical lamellas with a thickness of 40nm, the surface of the mineral needs to be polished, chemically etched, and investigated by Scanning Electron Microscopy (SEM) at very high magnification. In order to achieve a flat surface, the sample has to be first grained and then polished by a P4000 silicon carbide paper. Owing to the larger number of Si atoms contained in clinoptilolite compared to the Al atoms (5.4:1 for our zeolite sample), the chemical etching reaction needs to be based on the desilication process (dissolution of the framework silica with formation of soluble sodium silicate). In particular, a sodium hydroxide (NaOH) aqueous solution (0.2M) can be conveniently used for the clinoptilolite mineral etching with an etching time of a few hours (at room temperature). An etching treatment based on the dealumination reaction is not adequate since it can cause only lattice defects formation.