Seeing the effect of radiation damage

The rock matrix contains quartz, plagioclase feldspar, microcline feldspar and biotite mica. The greenish brown flake of biotite shown in the centre exhibits many dark brown circular features resembling cigarette-type burns. These features are known as pleochroic halos and are a diagnostic feature of biotite. These halos are interesting as they are isotropic compared to the surrounding material which is anisotropic. The halo in the centre of field shows a small brightly coloured crystal of zircon which causes the dark brown effect due to a process called metamictization. This process is the radioactive decay and destruction of the crystal structure surrounding the zircon and the affected area becomes amorphous and hence isotropic.

Diatoms - Jewels of the Sea

Diatoms are unicellular algae that are found wherever there is water and sufficient light to stimulate photosynthesis. The cells may be free floating (planktonic) or attached to a substratum (sessile). The diatom cell possesses the property of being able to surround itself with a more or less rigid box-like (like a covered petri dish) skeleton of hydrated silica called a frustule. The classification of diatoms is largely based on frustule form and sculpture. Diatoms range greatly in size from 5 – 2000 μm in length, although most species encountered are in the size range 20 – 200μm. 

How Do Flies Eat?

Fly Proboscis observed with a Motic B1 Upright Microscope

Flies have a special mouth part called a proboscis which, much like a straw, is used to drink liquids. The proboscis of the fly is a fascinating microscope object and in fact has been used on microscopy studies for a long time. The main interest is the tracheal ring structures which look spiral under low power but they are not.

Traveling back to the Jurassic period!

Antique sample of a Pterodactyl Rib under a Motic B1 upright microscope

Pterodactlys were winged reptiles who lived in the Jurassic period about 150 million years ago. The specimen is a portion of a transverse section of rib (approx. 1.8mm wide) and was taken from the slate mine area of Stonesfield (Oxford, England) and has been prepared as a thin section and dated June 1855. Pterosaur bones are difficult to cut and polish to a thin section without losing material. It is a testament to the preparer that the paleohistology details are clearly visible.