Reticulite is like glass in rock form… A frothy volcanic rock that forms during vigorous fire-fountaining of lava. It is so full of bubbles that it floats on water. It is like very fine pumice made of glass, and has the lowest density of any rock, with a porosity of up to 98 percent. The open honeycomb network of bubbles (vesicles) results from the bursting of cell walls against one another during vesiculation. I got a small sample of this silicate rock from a colleague in geophysics, and mounted it with doubled-sided tape in a paper slide. One really needs to see this in 3 dimensions and the structure is so fragile, that compression between slides or tape breaks the glass-like skeleton, but still allowed me to see the pores and pillars of the reticulate structure. Patterns of nature in glass… from a volcano!