Macusanite is a natural volcanic glass, which is produced by the rapid cooling of magma during a volcanic eruption. Since it typically contains concentrations of uranium, it can be used for fission-track dating. Understanding the fission-track formation process and its morphology in natural volcanic glass is of major importance in this dating method. Therefore, in this work the latent fission-track structure was investigated using the geometry evolution of etched tracks. This evolution was characterized as a function of the chemical etching time via optical microscopy and atomic force microscopy. In this way, measurements of track diameters and theoretical estimation of track depths of normal incident fission fragments were made in order to determine the bulk and track etch rates. As a result, both rates yield constant values, and therefore the defect density along the fission fragment trajectory can be considered constant.