£1.00 – £2.74
Gabbro igneous rock specimens from Balmedie quarry, Aberdeen, Scotland which exhibit a coars grained texture from the crystals. Formed as a mafic pluton intrusion, the samples contain pyroxenes such as augite along side plagioclase feldspar, amphibole and olivine crystals. They are derived from a body known as the Belhelvie basic intrusion which the parent unit being the Caledonian Supersuite. Samples exhibit a grey colouration and density and are suitable for the more serious or professional collector or higher educational use to differentiate similar looking igneous rocks with different compositions and origins. Available in three sizes, the specimens come supplied in a card tray with an information label.
Gabbro is an igneous rock which exhibits a phaneratic coarse grained texture, with crystals being visible with the naked eye. It is an intrusive rock composed of mafic minerals such as pyroxenes, mainly augite, along with plagioclase feldspars and minor occurrences of amphibole and olivine, the latter of which can give the rock, which is a grey colour, a slightly green tint. Gabbros form as intrusive igneous bodies such as plutons, deep beneath the earths surface as a holocrystalline rock when magnesium (plagioclase) rich and iron (augite) rich magma cools slowly, resulting in a coarse textured rock. These particular rock samples come from Balmedie quarry in Aberdeen, Scotland, UK and exhibit classic gabbro features explained above, with samples being fairly dense when held due to the amount of pyroxene minerals present. It is suspected that this igneous body, known as the gabbroic complex formed during the Ordovician period and is part of the Belhelvie basic intrusion which is in turn a smaller unit of the Caledonian Supersuite. The samples are ideal for the more serious collector and higher level education to establish that although on the surface, igneous rocks may 'appear' similar but their chemistry and mineralogy differ as well as their origins. Specimens are available in three sizes and come supplied in a card tray with an information label.