<?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">rubidium</topic></authority><related type="broader"><topic>nonferrous metal</topic></related><related type="broader"><topic>elements</topic></related><variant type="other"><topic>Rb</topic></variant> <note xml:lang="en"><![CDATA[ Pure metallic element having symbol Rb and atomic number 37; soft, silvery white, and very reactive, rubidium is found as a trace constituent of various alkali minerals. It is used in photoelectric cells and as a catalyst.  ]]></note></mads>