hardebank, noun

Forms:
Also hard bank, and (formerly) hardibank.
Origin:
AfrikaansShow more Afrikaans, combining form of hard + bank ledge, shelf.
Geology, Diamond-mining
a. The hardest form of blue ground, unweathered because lying at considerable depths. b. rare. A mass of mineral matter, formed at a later stage than the blue ground and intruding into it (see quotation 1921). Also attributive.
1905 H. Kynaston in Flint & Gilchrist Science in S. Afr. 300The Schuller No. 1 pipe consists to a great extent of very hard blue-ground, resembling the Kimberley ‘hardibank’.
c1922 Off. Yr Bk of Union No. 6, 1923 (Union Office of Census & Statistics) 603There are also found imbedded..larger fragments, moderate boulders and even greater masses of rock, which have come to be known under the name of ‘floating reef’. Where these inclusions have been found to be true kimberlite..they have been commonly alluded to in mining parlance as ‘Hardebank’; but, owing to a similarity in appearance, this term was equally applied to the material derived from certain intrusive dykes of later age that are found sometimes traversing the ordinary pipe rock.
1965 Hamilton & Cooke Geology for S. Afr. Students 275Below the limits of oxidation, the same rocks (sc. tuff-like and brecciated kimberlite material) form the familiar blue ground, and the more solid and better preserved material at depth is known as hardebank.
1971 A.E. Schoch in Std Encycl. of Sn Afr. IV. 31It is also more difficult to recover diamonds from the deep-seated, un-weathered kimberlite (the ‘blue ground’ and ‘hard bank’).
1971 P.A. Wagner Diamond Fields of Sn Afr. 27In the soft blue ground occupying the upper levels of the pipes there are occasionally found rounded masses of comparatively well-preserved kimberlite up to five feet in diameter which generally go by the name of ‘Hardebank boulders’...As greater depths are attained in the mines the products..are replaced in increasing measure by ‘hardebank’ or kimberlite, the parent rock, to the trituration and decomposition of which they owe their origin.
The hardest form of blue ground, unweathered because lying at considerable depths.
A mass of mineral matter, formed at a later stage than the blue ground and intruding into it (see quotation 1921). Also attributive.

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19051971