tufa
Meaning
a porous limestone rock formed by the precipitation of calcium carbonate from water, especially around mineral springs.
Usage
the cliffs along the lake are composed primarily of soft, crumbly tufa.
the ancient roman aqueduct was constructed using blocks of local tufa.
tufa deposits often form around hot springs where calcium-rich water emerges.
Etymology
The word "tufa" entered English in the late 18th century from Italian, where "tufo" denotes a porous rock. The Italian term itself derives from the Latin "tōfus," which referred to a soft, porous stone. This Latin word is believed to be of pre-latin, possibly oscan or sabine, origin, reflecting the local volcanic geology of Italy. The Modern English usage has narrowed specifically to a lightweight, porous limestone formed by the action of mineral-laden water, distinguishing it from the harder, volcanic tuff, which shares a similar etymological ancestry.
Analysis
This word is a loanword adopted as a single, unanalyzable unit in Modern English.