Mine Terms G

Cornish Mine Terms

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Term	Definition	Examples

Gangue	The Valueless mineral found within a a lode. Dressing will involve seperating the ore from the gangue.	Copper ore dressing terms
Gozzan (Gossan)	Weathered deposits of rock at the top of a load (the backs). It is the upper part of a lode near the surface and is stained red by iron minerals.Sometimes called the "Iron Hat". Water leaches the minerals from this region and they are re-deposited lower down in a Zone of secondary enrichment.
Granite	Igneous rock formed of crystals of felspar,quartz and mica with some assessory minerals.Granite was formed by the intrusion of magma into existing sedimentary rocks.A spine of granite runs from Dartmoor to the Scillies and it is this structure that forms the bases of Cornwall's minerals wealth. Twelve outcrops of the rock exist, the granite intrusion occurred about 280 million years ago in the late carboniferous period (in the Variscan orogeny a period of major earth movements). Dartmoor: In Devon, Largest and Highest outcrop Bodmin Moor:Largest outcrop in Cornwall Hensbarrow:North of St Austell Carnmellis: West of Falmouth Lands End Kit Hill and Hingston down: Small outcrops East of Bodmin Moor Castle-an-Dinas:North of Hensbarrow St Agnes Beacon:On the North Coast Carn Brea:Small outcrop North of Carnmellis Carn Marth:Small outcrop North of Carnmellis Godolphin :St Michaels Mount area Scilly Isles It is believed that the intrusion (batholith) is between 20Km to 10km thick, with Dartmoor forming the thick end of the wedge. The Width at its base is about 40-60km giving a total volume ofd 68,000Km3! Ref The Geology of Cornwall:University of Exeter Press Lodes are formed within the fissures caused by the intrusion and subsequent cooling of the Granite.
Grizzly	A series of narrow bars on which lumps of rocks were sorted for size.	S Caradon Grizzly remains
Grass	The surface of a mine as opposed to underground. Ore brought to grass is ore brought to the surface.