Editing Jasper (section)

===Basanite<span class="anchor" id="basanite"></span> and other types of touchstone===
<blockquote>Basanite is a deep velvety-black variety of amorphous quartz, of a slightly tougher and finer grain than jasper, and less splintery than hornstone. It was the ''Lydian stone'' or ''touchstone'' of the ancients. It is mentioned and its use described in the writings of [[Bacchylides]] about 450&nbsp;BC, and was also described by [[Theophrastus]] in his book ''On Stones'' ([[Ancient Greek]] title: {{math|Περὶ λίθων}}: ''Peri Lithon''), a century later. It is evident that the touchstone that [[Pliny the Elder|Pliny]] had in mind when he wrote about it was merely a dense variety of [[basalt]].<ref>{{cite book |last1=Dake |first1=H.C. |last2=Fleener |first2=Frank L. |last3=Wilson |first3=Ben Hur |year=1938 |title=Quartz Family Minerals: A handbook for the mineral collector |publisher=Whittlesey House (McGraw Hill)}}</ref></blockquote>

Basanite (not to be confused with [[bassanite]]), ''Lydian stone'', and [[radiolarite]] (a.k.a. lydite or flinty slate) are terms used to refer to several types of black, jasper-like rock (also including [[tuff]]s, [[chert]]s and [[siltstone]]s)<ref>{{cite journal |last1=Moore |first1=D.T. |last2=Oddy |first2=W.A. |date=1 January 1985 |title=Touchstones: Some aspects of their nomenclature, petrography and provenance |journal=Journal of Archaeological Science |volume=12 |issue=1 |pages=59–80 |doi=10.1016/0305-4403(85)90015-9 |bibcode=1985JArSc..12...59M }}</ref> which are dense, fine-grained and flinty / cherty in texture and found in a number of localities. The "Lydian Stone" known to the [[Ancient Greeks]] is named for the ancient kingdom of [[Lydia]] in what is now western [[Turkey]]. A similar rock type occurs in [[New England]]. Such rock types have long been used for the making of [[Touchstone (assaying tool)|touchstones]] to test the purity of [[precious metal]] [[alloy]]s, because they are hard enough to scratch such metals, which, if drawn (scraped) across them, show to advantage their metallic [[Streak (mineralogy)|streaks]] of various (diagnostic) colours, against the dark background. There are, confusingly, not one but two rocks called basanite, one being a black form of jasper and the [[Basanite|other]] a black volcanic rock closely akin to basalt. Add to this the fact that many different rock types – having in common the colour black and a fine texture – have, over the ages, been pressed into service as touchstones and it will be seen that there is ample scope for confusion in this [[petrology]]- and [[mineralogy]]-related field of study.<ref>{{cite web |title=Basanite |date=15 October 2012 |website=Mindat.org |url=http://www.mindat.org/min-9173.html |access-date=24 March 2013}}</ref>