Minerals

tourmaline-crystal The magazine has regular featured mineral article most issues, everything from creation, abundance to crystal lattice and structure.
Rocks, stones crystals, gems all formed from minerals or the combination of, made up of atoms and electrons and formed with distinctive characteristics, shapes and structures.
Often formed by volcanic activity, magma, compression and evaporation of water.
Several known structures are seen including cubic, tetragonal,hexagonal,monoclinic, triclinic, orthorhombic.
The magazine always has a range of suppliers that stock minerals both common and hard to find.

Excerpt from report on tin minerals in issue 40

 

 

 

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Rock and Mineral Collections of the Sedgwick Museum, Cambridge

 The Sedgwick Museum is part of the Department of Earth Sciences,University of Cambridge. The museum was founded in 1728 when Dr John Woodward bequeathed the geological part of his enormous collection to the university.


WOODWARD'S BEQUEST is still almost intact and can be seen in the present museum in its original walnut veneered cabinets. The main collections of the museum are divided into three: fossils, rocks and minerals. What follows is a brief history and description of the last two.
The rock collection has over 150,000 specimens from all over the world.


The first was collected in the time of Elizabeth I when Martin Frobisher was exploring for the North-West Passage around the north of America. He found rocks with a golden mineral and brought some back. His alchemists assured him that there was gold in the rock so he raised the money to take three ships and bring back a great quantity - unfortunately the mineral was not gold but a mica. Frobisher was put in jail, only narrowly escaping with his life, as one of the investors was the queen herself. What happened to the alchemists is not recorded. Moral: make sure your alchemists put their money where their mouths are. "Frobishers Gold" came into the collection in the 1920s.


Charles Darwin made several big contributions to geology, which have been overshadowed by his work on evolution.
The specimens he collected on the voyage of the Beagle (1831-1836), or at least those which survived from storage at Down House, came to the university in 1896. From what he saw on the voyage Darwin noted, amongst other things, that there might be connections between earthquakes and volcanoes, that the layering in gneisses formed during metamorphism and that nearly all oceanic islands were built on volcanoes.

Many other expeditions have contributed specimens, from the Arctic to the Antarctic, and from the floors of the oceans to the highest rock on Everest, though nowadays most additions come from people doing Ph.D.s at Cambridge.
THE MINERAL COLLECTION Mineralogy was established at Cambridge in 1809 and there are now over 40,000 specimens in the mineral collection, making it the second or third biggest in Great Britain. Some can be traced to 1786, when the Duchess of Portland's 'museum' was sold, though they did not reach Cambridge until 1922, when Spencer George Perceval bequeathed them.
Four big collectors provided over half the specimens
Sir Abraham Hume (1749-1838), Joseph Carne (1782-1858), Henry Brooke (died 1856) and Thomas Wiltshire (1826-1902). Between them they show several different types of collector. Hume was a wealthy gentleman who took an amateur interest in mineralogy and built up a collection of some 6,00 specimens with a strong hand in calcite. Brooke worked in the insurance industry but also published extensively on mineralogy, and named several new species. Brooke's collection includes the oldest surviving specimen of phosgenite from Cornwall. Carne worked in the copper smelting industry in Cornwall and, though he probably did not collect in the field, he obviously had close contact with mines and miners, and used them to acquire specimens. Finally,Wiltshire was an academic geologist, professor at King's College, London, but specialised in palaeontology. It appears that he built up his collection by purchase in his last 20 years of life.

The rate of growth of the collection has been low in the last 15 years as purchase funds havebeen cut, so we have no examples from the newer localities now producing in China and South America. An occasional donation has helped keep things ticking over. Since 1988 there has been a small mineral gallery in the Sedgwick Museum which has excellent modern displays,but of course only a small part of the collection can be shown so most of the specimens are in a new air conditioned store. Access to the specimens, and to information about the collection can usually be obtained by arrangement.

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