Isle of Pitchstone

arran pitchstone Pitchstone rock is a variation of natural glass and similar to obsidian. Pitchstone seems to be a rare beastie found in a couple of places in Scotland, one of those is the Isle of Arran.

This natural glass rock is called Pitchstone or Pechstein in German, as it resembles pitch that makes it look differently dull to obsidian.

The other easily searched and found geological location for pitchstone is at the wonderfully named Specimen Mountain (Rocky Mountains), Colorado, USA. A couple of other locations or formations that mention pitchstone are Lake Taupo in New Zealand and Pitchstone Plateau in Yellowstone National Park.

Is pitchstone type glass fairly rare or is it just that it is called other names – either known as something different now or in the past or in other languages is not easily searched for?

What is pitchstone?

pitchstone obsidian arran
Pitchstone seems to be a specific variation of the more common volcanic obsidian glass that is said to be formed by volcano activity or formed in and around and associated with dikes, partly due to its surprisingly high water content.

Pitchstone is a dull black glassy volcanic rock formed when a felsic, viscous lava or magma cools quickly. It is similar to obsidian but is defined by the International Union of Geological Sciences as having a higher water content. It is a volcanic glass, however, unlike a glass pitchstone has an irregular, hackly fracture not a conchoidal fracture, this is due to its coarser (than obsidian) crystal structure. pitchstone has a resinous lustre, 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 extrusive rock that is very resistant to erosion.
Pitchstone | wikipedia

Isle of Arran and Scotland’s pitchstone

arran pitchstone 1

The pitchstone ridge of An Sgùrr on the Isle of Eigg, Scotland, was possibly formed as a lava flow in a valley.

Pitchstone from the Isle of Arran was used as the raw material for making various items from the Mesolithic through the Neolithic to the Early Bronze Age. Mesolithic use appeals 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 | wikipedia


The rock is pitchstone, and the curved surfaces is due to cooling paterns, as are the prominent joints breaking the surface into rectangles
Judd’s Dykes | University of Glasgow

In Scotland, all archaeological pitchstone derives from outcrops on the Isle of Arran, in the Firth of Clyde, and on the source island pitchstone-bearing assemblages include diagnostic types from the Mesolithic, Neolithic and Early Bronze Age period. Off Arran, pitchstone-bearing assemblages never include Mesolithic types, such as microliths, suggesting a post Mesolithic date. This suggestion is supported by worked pitchstone from radiocarbon-dated pits, where all presently available dates indicate that, on the Scottish mainland, Arran pitchstone was traded and used after the Mesolithic period, and in particular during the Early Neolithic period.
Arran pitchstone (Scottish volcanic glass): New dating evidence

Isle of Arran’s Great Pitchstone Sill


The Clauchlands Sill (top) and the “Great Pitchstone” Sill (bottom), intruding Permian sandstones between Clauchlands Point and Corrygills Point. The Clauchlands Sill is about 40 feet thick, and the Great Pitchstone Sill about 12 feet.

The pitchstone of the Great Pitchstone Sill, an extremely fine grained, bottle-green rock, with a resinous lustre. It contains scattered needles of microlites and feathery growths made up of small crystallites in a glassy matrix.

A fine example on Arran would be the Corrygills Pitchstone Sill (NS 051338), which forms the large cliffs on the shore below the Clauchland Hills.
Igneous Rocks – Pitchstone | University of Glasgow

Pitchstone, volcanic glass and EU geology

If pitchstone is rare and a variation of volcanic glass can it be used to help work out Electric Universe geology processes, formations and events?

If it is a transmutation of the host material into a different type of volcanic glass can this be used to work out thing what might have happened? Or did not happen to other normal volcanic glasses found around the world?

If they were formed in water then what clues can this give about what was happening at that time, what process was occurring and how it reacted?

Looking for these rarer variations or the next steps of a mineral or element being transformed is perhaps a good way to work out what electromagnetic things might have happened to local geology. Be they electromagnetic forces, EM energy, electrochemical, EM spectrum waves created changes in the valency, electrons, anions, cations etc