<?xml version="1.0" encoding="utf-8"?><mads xmlns="http://www.loc.gov/mads/" xmlns:mods="http://www.loc.gov/mods/v3" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.loc.gov/mads/
mads.xsd"><authority><topic authority="http://AATesaurus.cultura.gencat.cat/aat/getty_en">tufa</topic></authority><related type="narrower"><topic>pietra di Mendicino</topic></related><related type="other"><topic>travertine</topic></related><related type="broader"><topic>sinter</topic></related><variant type="other"><topic>calc-tufa</topic></variant><variant type="other"><topic>calcareous tufa</topic></variant><variant type="other"><topic>tufa, calcareous</topic></variant> <note xml:lang="en"><![CDATA[ Calcareous, porous limestone formed by the precipitation of calcium carbonate at the vents of springs and geysers, along streams, or on the bottoms or shores of lakes. It is distinguished from travertine by generally being soft and easily crumbled. ]]></note></mads>