Bin Quarry

Also within

Aberdeenshire County

Condition (NatureScot)

Geology & landscape

Mining / Industrial: Quarry · Rock Type: Granite, Limestone

Landscape processes: Volcanic / Igneous

Description

BIN QUARRY Bin Quarry is located 4 km to the north-west of Huntly. The site provides a classic example of layered cumulate rocks (formed by crystals settling to the bottom of a magma body) which developed at a relatively early stage of gabbroic magma crystallization. The quarry exposes part of the Huntly-Knock intrusion and undoubtedly provides the best example of small-scale layered structures within the ‘Younger Basic’ intrusions (formed during the Caledonian mountain-building event). The rocks are broadly troctolitic (plagioclase and olivine bearing) to gabbroic (plagioclase, augite and olivine bearing) in composition, though individual layers may be ultramafic peridotites (olivine only). Sedimentational structures, such as graded bedding, provide evidence of gravity accumulation of crystals, and a ‘way-up’ indicator for the rocks. This shows that the layering, which dips steeply westwards, is overturned, indicating tectonic activity after the intrusion formed. There are also some minor granite-pegmatite sheets cutting the troctolites, which are in turn cut by later narrow veins. The narrow veins within the layered gabbros at Bin Quarry carry an unusual suite of hydrated calcium silicate minerals, in particular scawtite and tacharanite, two rare Scottish minerals. Scawtite development within the veins is unusual because normally it is found only at limestone contacts thermally metamorphosed, usually by heat from adjacent magma intrusions. The quarry has produced some of the finest silky vein xonotlite specimens known from the United Kingdom, which are of outstanding museum quality.