Pitchstone

Pitchstone is a dark coloured, glassy <a href="/facts/Volcanic_rock/ID3oPwtM">volcanic rock</a> formed when <a href="/facts/Felsic/0jpm1eSA">felsic</a> <a href="/facts/Lava/q2an5SVN">lava</a> or <a href="/facts/Magma/hRotHju9">magma</a> cools quickly. Since it is a <a href="/facts/Volcanic_glass/MFmUlyad">volcanic glass</a>, pitchstone may have a <a href="/facts/Conchoidal_fracture/2tg82TPw">conchoidal fracture</a>. Pitchstones may also contain <a href="/facts/Phenocrysts/jPVodoja">phenocrysts</a>, in which case it is a form of <a href="/facts/Vitrophyre/wb1GC61u">vitrophyre</a>. Pitchstone has a <a href="/facts/Resinous/r1uVThQ8">resinous</a> <a href="/facts/Lustre_(mineralogy)/TCobwMGC">lustre</a>, or silky in some cases, and a variable composition. Its colour may be mottled, streaked, or uniform brown, red, green, gray, or black. It is an <a href="/facts/Extrusive/AAFoj1BF">extrusive</a> rock that is very resistant to <a href="/facts/Erosion/gaGJXy0W">erosion</a>.
The pitchstone <a href="/facts/Ridge/vd9Waeml">ridge</a> of <a href="/facts/An_Sg%C3%B9rr_(Eigg)/TdyTk9ry">An Sgùrr</a> on the Isle of <a href="/facts/Eigg/paIyB5wK">Eigg</a>, <a href="/facts/Geology_of_Scotland/DWAICzXq">Scotland</a>, was possibly formed as a lava flow in a valley.
Pitchstone from the <a href="/facts/Isle_of_Arran/lhEDIeUd">Isle of Arran</a> was used as the raw material for making various items from the <a href="/facts/Mesolithic/XTNS0x3r">Mesolithic</a> through the <a href="/facts/Neolithic/wRS0Bnh4">Neolithic</a> to the <a href="/facts/Early_Bronze_Age/c09qWcTt">Early Bronze Age</a>. Mesolithic use appears to have been limited to the Isle of Arran itself, while in later periods the material or items made from it were transported around Britain.

Pitchstone open-in-new

Pitchstone