The Mineral collection at the Natural History Museum, and Flint Nodules along the River Thames

Natural History Museum
Yesterday we went to the Natural History Museum in South Kensington, on recommendation from Hedda, a friend of mine who also collects rocks. We were there largely to see their vast mineral collection and I wanted to see how their rocks were displayed - so we skipped all the animals and went straight for the geological section…


I wanted to be systematic and to read every single label in loving, adoringly attentive detail - but… after the first few hundred rocks and mineral names you begin to lose the will to want to absorb or comprehend it all. There are just too many rocks. So.. many... rocks........ The sheer volume is almost madness-inducing. And if you will believe the wikipedia entry on the Natural History Museum...

"J.E. Gray (Keeper of Zoology 1840-74) complained of the incidence of mental illness amongst staff: George Shaw threatened to put his foot on any shell not in the 12th edition of Linnaeus' Systema Naturae; another had removed all the labels and registration numbers fromentomological cases arranged by a rival. The huge collection of conchologist Hugh Cuming was acquired by the museum, and Gray's own wife had carried the open trays across the courtyard in a gale: all the labels blew away. That collection is said never to have recovered."

(I haven't been able to find any copy of Lynn Barber's "The heyday of natural history, 1820-1870" in order to verify the colourful stories quoted in the entry above but I have to admit I do enjoy the idea of the natural sciences being an attractor for the eccentrics...)


Here is a quick run through the NMH's collections:





Molybdenite (Grey plates with quartz prisms, from Baker's Mine, New South Wales, Australia)



Silver





Gold



Bismuth



Arsenic



lovely mass of dendritic growths



flattened cubo-octahedra



Rhodochrosite massive + tapering prisms



Chalcedony from Iceland (!!!)



Dartmoor Granite (commonly used in london curbstones)



Shap Granite (another commonly used British granite with pink feldspar)



Agates



Big lovely Geode



Iridescent massive



Slightly iridescent stalactite



Fantastic radiating bladed crystals



Another iridescent massive



"Iron froth"



Hematite



Crystal crust



Twin quartz crystal



Interpenetrant twin crystals



"Radiating crystalline in cavities of wad". Who comes up with these excellent names for the rocks?



Interlacing prisms



Bluish banded massive



Quartz



Siliceous Sinter in rods and convolutions



Sassolite



Aurorite



Calcite "Iceland Spar"



More Calcite



Even more Calcite



Mamilated Crust with Malachite and Wad



Botryoidal with Crystalline surface



Group of prisms with cerussite



Malachites



Aurichalcites + Malachites



Prehnite Geode



Removed Specimens



Rhodonite



Lepidolite



Stillbite



Whitlockite



Vivianite
Etc... There were more but near the end I was running through the aisles tearing my hair out whilst screaming "OH GOD, OH GOD, NOT MORE ROCKS". Also, any one who brings their small child into the geological section - and who is not willing to read every single label to their child - even though their child is shorter than the display cabinets in the museum (and thus unable to see any of the rocks) and then leaves their child free to have a run around the museum like a psychotic howling monkey should be roundly smacked and their child should be taken outside and given a free double expresso. And a free kitten. And a big massive sugary stick of Blackpool Rock. Yeah, I bet that'll teach them.

Has anyone actually managed to get through all the rocks? Or has everyone else fallen over after suffering the big fat massive rock photo-overload? Great, now I'll get on with the interesting part of this post...



FLINT NODULES IN THE RIVER THAMES

If there was one useful thing I picked up after going through a few thousand rocks, it was that I have learnt that the type of "Thames River rock" that I have been seeing strewn along the banks of the part of the Thames in London could be identified as "Flint" or "Nodular Chert".

I have been wondering about what kind of rocks they were for some time but no one could tell me and I did not have a geological dictionary nor the appropriate vocabulary to find what I was looking for. Visually, they are quite distinctive because they consist of a hard, waxy quartz type rock surrounded by a thin layer of something else.

The examples being displayed at NHM looked like this:



'FLINT' from the Chalk
Isle of Wight



'FLINT' enclosing chalcedony nodule
One might notice that they have chosen to describe it as 'FLINT' with the quotation marks around it. Apparently the terms "Flint" and "Chert" are often mixed up or used interchangeably in Britain...

From an information panel at the NHM: "Flint or chert? "

The inconsistent use of the terms 'flint' and 'chert' for siliceous deposits leads to much confusion. However, it is widely understood that flint is a synonym for chert often referring to nodules and bands within the Chalk of Europe. Whereas chert refers to siliceous deposits occurring in other limestones and sandstones.

Flint is formed by the concentration of mobilized silica from siliceous organisms within the carbonate host rock into voids such as burrows and along bedding planes. This process occurs during the early stages of burial. Since the process replaces the host rock, some flint nodules preserve the original features of the Chalk."

Example of Flint Nodule at NHM
If you ask me, it looks like the Thames Rocks are indeed "flint" nodules then. This is what I observed on the pebbled banks of the Thames in October:






If interested to poke about some rocks, you can find steps access to the River Thames along the south bank - there should be a couple not far from Southbank Centre / Oxo Building / Millennium Bridge.