Minerals of Scotland

SCOTTISH
AGATES

Scottish Agates
"Scotch Pebbles"

Introduction
Origin & Nature
Occurences, Types & Locations

with agate photographs from various Scottish sites.

 

Though Scotland may not produce the largest agates (there are exceptions),
Scottish agates rank among the best for their variety of forms
and for their subtle colouring.

 

"Scotch Pebbles"
Scottish Agates

"Scotch pebbles" are agates or agate fragments commonly collected from beaches after being worn out of the host rock. Agates are to be also found in situ (in the host rock).

Some locations of either type have been over-collected in the past and are no longer very productive; while others can give surprises...

Agates from Scotland are found in situ in the andesite and basalt lavas of Devonian age located in the Midland Valley.

There are two main areas in Scotland where these lavas are to be found - in the east, centred around the former counties of Angus and Fife and, on the south-west coast, in Ayrshire.

Agates may also be found in the Tertiary basalt lavas of some areas on the west coast.

Regardless of their occurence, this variety of quartz can make beautiful natural objects when polished.


SCOTTISH AGATES

Details of Scottish agates from classic sites
in Perthshire, Angus & Ayrshire.

   

Occurence

In all these areas, beach agates
can be found. Where the lavas extend out to sea, agates can be weathered out by sea erosion and subsequently washed onto nearby beaches
by the action of currents.

The agates of the Devonian lavas generally have a wide variety of colouring and form and are normally the source of the best agate specimens to be found in Scotland.

The Tertiary basalt lavas, on the other hand, have a more restrictive colour palette to impart upon the agates
they produce, in comparison to their Devonian relations.

SCOTTISH AGATE
LOCATIONS

Map showing (in dark text)
some of the more important
agate-bearing areas of Scotland.

Fortification AGATE
Norman's Law, Fife, Scotland.

     
Agate Types

Nearly all the generally accepted, descriptive agate forms or types are to be found in Scotland, including hemi-agate, sagenitic agate, onyx agate, moss agate, scenic agate...
to name but a few.

However, it is the more common "fortification agate",
of typically concentric banded patterns, which is prevalent throughout most agate-bearing areas of Scotland.
Vein agate is far more restricted in its occurence.

It is quite possible to find two or more agate forms on the one example. Similarly, some sites can render a wide array of agate forms, while others are more limited with their patterns.

Hemi AGATE
Ferryden, Montrose, Angus, Scotland.

   

Locations

Some locations throughout Scotland are justly renowned
for the quality of agates they have produced. However,
some of these sites are now, unfortunately, almost history.

The factors which have caused this vary from the precise location having been lost through time, the sites are now difficult or impossible to access or, simply, the occurence
has become exhausted.

Examples of these include the classic "Blue Hole" site
near Montrose, in Angus, or that of Burn Anne in Ayrshire.

New collecting sites are occasionally uncovered.
Prime examples include Ethiebeaton and Ardownie Quarry, Monifieth, both near the city of Dundee, in the old county
of Angus, Tayside Region.

Specimens from the latter site were rated of the best quality
for Scotland. Unfortunately, the locality was short-lived
and is no longer accessible.

AGATE ("Flame Agate")
Scurdie Ness, Montrose, Angus, SCOTLAND.

   

EASTERN SCOTLAND:
Agates are found in Angus, particularly the Montrose area, the northern side of the Tay Estuary around Dundee and inland, in the Sidlaw Hills.
Farther north, they are also to be found in Kincardineshire.

Other sites include the southern side of the Tay Estuary and the Ochil Hills, both in Fife - with the Norman Law area being particularly well-known
and productive.
Further inland, in Perthshire,
there are also numerous sites.

TERTIARY LAVAS:
The Tertiary basalt lavas of the west coast of Scotland are better known for their zeolite mineral specimens.
Agate localities are less common and/or less well known.

Nevertheless, agates are to be found
on the islands of Mull and Rhum
and elsewhere.
New finds remain to be made.

SOUTH-WEST SCOTLAND:
Devonian agates are found in the county of Ayrshire around Dunure, south of the town of Ayr, and farther south.
Small restricted occurences, where these rocks outcrop at the surface, are also found inland.

SOUTHERN UPLANDS:
Another agate area of note is the Cheviot Hills in the Southern Uplands - straddling the border region of England and Scotland. Several agate types, including vein agate are found.

     
     

Vein AGATE - Galston, Ayrshire, Scotland.
Section with calcite breccia showing faulting.

"Inner Space" - microscopic view of part of the agate on the left, showing yellow, iron-bearing,
colloidal spherules which imbue the agate with colour.

 
     
   

Agates Plus - A Bonus Free Gift!

Other minerals may be found as inclusions in agates. Commonly, these minerals are calcite, dark green, "mossy" celadonite and occasionally fibrous/ acicular, zeolite mineral species ("sagenitic agates").

Quartz varieties such as rock crystal, smoky quartz and amethyst are also found in agates.

Some agates from the Tertiary lavas of Mull contain inclusions of very small, simple cubic crystals of golden pyrite.

NOTE
Permission is normally required to gain access to most inland localities and this should be sought from the relevant authorities beforehand!

Sagenitic AGATE - Kinnouill Hill, Perthshire.
Detail showing inclusions of small, needly sprays of a zeolite mineral.

   

the end

Central Scotland - East

SW Scotland

Scotland &
Type Localities

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References/ Further Reading

Book -
"Agates" H.G. MacPherson. (1989). (National Museum of Scotland & British Museum (Natural History) publication.)
- recommended.

UK Journal of Mines & Minerals
vol.7 pp. 13-17 "Colour in Scottish Agates." R. Field. (1989).
vol. 14 pp.17-20 "Agates from Ardownie Quarry, Monifieth, Tayside, Scotland." S.M. Ingram. (1994).

© Minerals of Scotland - 2008.