<?xml version="1.0" encoding="utf-8"?><!DOCTYPE Zthes SYSTEM "http://zthes.z3950.org/xml/zthes-05.dtd">  <Zthes><term><termId>31344730</termId><termName>chert</termName><termType>PT</termType><termNote><![CDATA[ Fine-grained, dense sedimentary rock consisting of interlocking crystals of quartz approximately 30 microns in diameter. Chert and its varieties, such as flint, are non-gem varieties of cryptocrystalline-granular quartz. These stones chip very easily and thus may be fashioned into tools with a sharp edge; they are also used for building. ]]></termNote><termCreatedDate>2026-03-30 20:32:59</termCreatedDate><relation><relationType>UF</relationType><termId>31344731</termId><termName>cherts</termName><termType>ND</termType></relation><relation><relationType>BT</relationType><termId>31375454</termId><termName>sedimentary rock by composition</termName><termType>PT</termType></relation><relation><relationType>BT</relationType><termId>31320469</termId><termName>mineral</termName><termType>PT</termType></relation><relation><relationType>BT</relationType><termId>31344506</termId><termName>quartz</termName><termType>PT</termType></relation><relation><relationType>NT</relationType><termId>31375393</termId><termName>flint</termName><termType>PT</termType></relation><relation><relationType>NT</relationType><termId>31375395</termId><termName>jasper</termName><termType>PT</termType></relation></term>  </Zthes>