Thick carbonate scale samples from the Újszeged geothermal cascade system sampled from a pipe between the production well and the buffer tank. (a, b) Macroscopic images of the sample G-03 (total length of the scale bar: 5 cm). (c) Outer part of the sample G-03, showing a fibrous (F) morphology. Substrate material (pipe, P): carbon steel. (d) Inner part of the sample G-03, showing a complex morphology with fibrous (F) to botryoidal (B1 to B3) zones. Note: B1/B2 boundary (an intermittent brownish stained layer) separates seasonal (annual) operational rhythms. Fine lamination represents effects related to the periodical (weekly or daily) operational phases.