<?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">Potomac breccia</topic></authority><related type="broader"><topic>breccia</topic></related><variant type="other"><topic>Potomac marble</topic></variant><variant type="other"><topic>Potomic breccia</topic></variant><variant type="other"><topic>breccia, Potomac</topic></variant><variant type="other"><topic>calico marble</topic></variant><variant type="other"><topic>calico rock</topic></variant><variant type="other"><topic>marble, Potomac</topic></variant><variant type="other"><topic>marble, calico</topic></variant><variant type="other"><topic>rock, calico</topic></variant> <note xml:lang="en"><![CDATA[ A striking breccia quarried in the Blue Ridge Mountains in Maryland and Virginia; it consists mostly of limestone, quartz pebbles, and multicolored fragments ranging from sand grains to cobbles, all cemented together in a calcareous matrix. It can be extremely difficult to work as the hard pebbles tend to break away from the softer matrix. ]]></note></mads>