Author: More than a Dodo

What’s on the van? – Granite

This week’s What’s on the van? comes from Dr Dave Waters, Curator of Mineralogical Collections and Monica Price, Head of Earth Collections.

The rock that goes home for holidays
Every year, a group of Oxford undergraduates travel to north-west Scotland to unravel the fascinating geological history of the area by studying the local rocks and how they relate to each other. They stop at various places to explore the geology, including the ‘multicoloured  rock stop’, an exposure of rocks in a road-cut north of Loch Laxford. This is where our sample of granite was collected in 1998.

It is very old, part of a suite of ancient Precambrian rocks known as the ’Lewisian complex’, named after the Hebridean island of Lewis. It formed about 1.7 billion years ago when magma – hot molten rock – was intruded into an even older metamorphic rock called a gneiss. The magma cooled down, forming crystals of different minerals: pink potassium feldspar, white sodium feldspar, transparent grey quartz, and black grains of biotite mica and magnetite.

The students learn to identify the minerals by studying thin sections of the rock, just 0.03mm thick, under a petrological microscope. This allows them to examine the distinctive optical properties of each mineral under polarised light. The Oxford Earth Sciences Image Store shows you what they can see.

Each year, this piece of granite travels ‘home ‘ with the students on their fieldtrip, and helps to teach them about the different kinds of rock they will see in the field. It is part of the large collections of rocks, fossils and minerals in the University’s Earth Sciences Department and the Museum of Natural History that are available for students to study.

What’s on the van? – Mosquito

This week’s What’s on the van? comes from Zoë Simmons, of the Museum’s Hope Entomological Collections.

The word mosquito (formed by mosca and diminutive ito) is from the Spanish or Portuguese for “little fly”. Approximately 3500 species of mosquito have been described to date. The females of a few species require a blood meal in order to lay fertile eggs but many more do not and of those that do, only a handful are disease vectors (a carrier of disease).

These few species however, are of global importance to the human race as they can transmit diseases such as Yellow Fever and Malaria. As a consequence, the mosquito has been dubbed ‘the most dangerous animal in the world’. A large amount of scientific research has been put into combating mosquitoes and the diseases that they carry, but some of the most important information has come from entomologists who have studied mosquito behaviour and lifecycles in detail. From this, scientists have been able to get a better and more complete understanding of the species and thus develop more effective methods of eradication and disease management.