We arrived at Croft quarry about 8.30am after an uneventful and clear run up the M1 to Leicester. From the main road all that could be seen was an unusual hill in the distance with a hint of cliff edge disappearing into the centre, something like a lopsided caldera. This bump on the landscape was the result of a plutonic intrusion some 500Ma ago. The quarry produces aggregate for road surfacing and is one of the five super quarries of Leicestershire. It's BIG! Without a sign post saying Croft Quarry one wouldn't have guessed anything was going on. (Well, it was Saturday!) To me the most striking feature was how clean everything seemed to be.

Two groups of us descended into the quarry, the first accompanied the Quarry's representative in his four wheel drive, whilst Alan & myself followed with Geoff at the wheel of his Paleo-Wagan MkIV. Bench after Bench we descended to the quarry floor. We were advised to abandoned Paleo-Wagan for the last hundred yards as it was getting rather step and slippery. Getting in under gravity - No Problem - Getting out could have been another story!

Big CAT on it's way to the Crusher with an 85 tonne load. Did we stop to let it pass?

We were supervised to the locality that Geoff had said gave the best chance of finding mineral specimens, fortunately quarry working wasn't occurring at that spot otherwise we would have been denied access!

Members caught between a Rock and a Hard Place!

The rock in the foreground is typical of what is being quarried. It is a granodiorite that visually looks like a uniform dark pink rock. Under a x10 loupe all the grains appear regular in size, about 0.5 -1.0mm. The composition is composed of quarts, pink feldspars and a black mineral, probably hornblende (don't take what I say as gospel, I'm a bit rusty at this). In the sample I looked at there was very little mica if any (biotite). (Occasionally, small palm sized areas of a variation in the mineralisation occur. Sorry to be vague but I got sidetracked and forgot to take a close look.) This is the material they process into aggregates. Last year's production ran to 3.8 million tonnes. The classification for a Super Quarry is production in excess of 2 million tonnes per annum. From the preparation point of view this rock reprocesses extremely well, breaking into regular size chunks with no preferential cleavage.

Geoff is smiling as he and Alan have found a small pocket to work in a relatively "safe spot!"

Mineral specimens of Calcite and Analcime were found, but not in abundance, and not without some luck. I do believe the collectors amongst us would have been disappointed by this trip.

Although the granodiorite is quite uniform throughout the quarry, there was evidence of what looked like folding structures in the upper parts. The lower sections seemed featureless when viewed from our collecting location but a closer look did reveal some evidence of folding. It is difficult to postulate how these features formed but my belief is that they are the result of contraction as the intrusion cooled. An analogy would be the effect of the way a cake can sage when removed from the oven but as a my friendly local baker always used to say, "A well done tart always rises in the middle." I'm sure I don't know what he means?

Continued:                                                                         R Coleman 13/6/2002