Petrology & meteorology through a microscope with thin rock sections

Searching for micrometeorites on my roof in Lichfield

Having seen it done on BBC Sky at Night TV programme, I decided to have a go myself. For the last few weeks, I have put a strip of wood with neodychromium magnets screwed onto it in the gutter from our roof……in the hope of picking up these tiny visitors from the solar system. If I find them, they will be round/egg shaped from melting as they heat up in the Earth’s atmosphere during their fall to the ground (roof).

As you can see below, I washed off what was stuck to the magnets, then filtered it and used another neodychromium magnet to try and retrieve magnetic material from what remained. Most of it was organic debris (not sure why that stuck to the magnet!) – but resolutely stuck to magnet and difficult to remove was a reasonable amount metallic dust.

The photos show that sadly this is composed of small angular rust particles – I could not find the tell tale round structures that could be meteorites.

The magnets are back in the gutter.


Extracting possible micrometeorite (magnetic) particles from gutter collector:

What I found – tiny angular pieces of metal (totally opaque as metallic):

Helicon Focus 3D image and model:

Lichfield micro-meteorite project – making and setting up collector

On BBC Sky at Night TV show a few months ago, they collected micro-meteorites from roof collection at the Norman Lockyer Observatory in Sidmouth, UK. Rhys and I ordered some neodychromium magnetd and today we mounted them on a piece of spare wood using some small screws through their central holes. We put the wood and magnets, magnet side down, in the guttering on the front of our house in Lichfield, UK.

Hopefully, this will extra small metallic debris from the water running off the roof when it rains over the next few months. Again hopefully some of this will turn out to be micro-meteorites.

Andy and Rhys

Campo del Cielo meteorite thin section – microscopy using Zeiss IM microscope (not using polarisation)

I have waited some considerable time for this meteorite thin section to arrive – from the famous Campo del Cielo fall. Largely iron (black areas), there are also some minerals.

The following photos are NOT polarised.


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Ozona Texas meteorite thin section microscopy Leitz Laborlux 161117

Second light for the Leitz Laborlux 11 microscope today was to image my thin section microscopic slide of a meteorite fragment from Ozona, Texas. All images using Bresser MikrOkular camera – there is no polarisation in these images as the Laborlux 11 version I have does not have polarised filters.

The information supplied with the thin section states that the Ozona meteorite was found in Crockett County, Texas, USA, in 1929. There were several pieces weiging a total of 127.5kg. It is a classic H6 Chronite. My sample has come from the Michael Cottingham Meteorite Collection.


Information on chrondrites:

The following information on Chrondrite meteorites comes from Wikipedia. Chondrites are stony (non-metallic) meteorites that have not been modified due to melting or differentiation of the parent body. They are formed when various types of dust and small grains that were present in the early solar system accreted to form primitive asteroids. They are the most common type of meteorite that falls to Earth (around 85% of all meteorites). Their study provides important clues for understanding the origin and age of the Solar System, the synthesis of organic compounds, the origin of life or the presence of water on Earth. One of their characteristics is the presence of chondrules, which are round grains formed by distinct minerals, although the proportion of the meteorite that is composed of chrondrules varies considerably – they normally constitute between 20% and 80% of a chondrite by volume. Chondrites can be differentiated from iron meteorites due to their low iron and nickel content. Other non-metallic meteorites, achondrites, which lack chondrules, were formed more recently. Chondrites are divided into about 15 distinct groups on the basis of their mineralogy, bulk chemical composition, and oxygen isotope compositions. The various chondrite groups likely originated on separate asteroids or groups of related asteroids. Each chondrite group has a distinctive mixture of chondrules, refractory inclusions, matrix (dust), and other components and a characteristic grain size. Other ways of classifying chondrites include weathering and shock. Chondrites can also be categorized according to their petrologic type, which is the degree to which they were thermally metamorphosed or aqueously altered (they are assigned a number between 1 and 7). The chondrules in a chondrite that is assigned a “3” have not been altered. Larger numbers indicate an increase in thermal metamorphosis up to a maximum of 7, where the chondrules have been destroyed. Numbers lower than 3 are given to chondrites whose chondrules have been changed by the presence of water, down to 1, where the chondrules have been obliterated by this alteration.

The information from Wikipedia above there places the Ozona meteorite (as a classic H6 Chrondrite) in the category of Ordinary Chrondrites. Being H6, the chrondrules are less distinct than in some other meteorite thin sections in my collection.

Some features you may wish to look out for in my pictures below are variations in colour in the mineral content, orientation of mineral crystals in same direction (seen particularly in one of the high magnification images), very dense opaque material between the mineralised areas (?iron), areas with larger and others with small mineral crystals, and the shapes of the crystals in the high magnification images.

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Microscopy of Garnet Stone from Scotland

The following photos are microscopic images using Zeiss IM microscope of Garnet Paragneiss (Precambrian) from Loch Duich (Glenelg Inlier), Scotland.

This slide was obtained with number others from ebay second hand.

Information on Garnet from Wikipedia:

Properties: Garnet species are found in many colors including red, orange, yellow, green, purple, brown, blue, black, pink, and colorless, with reddish shades most common.

A sample showing the deep red color garnet can exhibit. Garnet species’ light transmission properties can range from the gemstone-quality transparent specimens to the opaque varieties used for industrial purposes as abrasives. The mineral’s luster is categorized as vitreous (glass-like) or resinous (amber-like).

Crystal structure: Garnets are nesosilicates having the general formula X3Y2(Si O4)3. The X site is usually occupied by divalent cations (Ca, Mg, Fe, Mn)2+ and the Y site by trivalent cations (Al, Fe, Cr)3+ in an octahedral/tetrahedral framework with [SiO4]4− occupying the tetrahedra. Garnets are most often found in the dodecahedral crystal habit, but are also commonly found in the trapezohedron habit. (Note: the word “trapezohedron” as used here and in most mineral texts refers to the shape called a Deltoidal icositetrahedron in solid geometry.) They crystallize in the cubic system, having three axes that are all of equal length and perpendicular to each other. Garnets do not show cleavage, so when they fracture under stress, sharp irregular pieces are formed (conchoidal).

Hardness: Because the chemical composition of garnet varies, the atomic bonds in some species are stronger than in others. As a result, this mineral group shows a range of hardness on the Mohs scale of about 6.5 to 7.5. The harder species like almandine are often used for abrasive purposes.

Magnetics used in garnet series identification: For gem identification purposes, a pick-up response to a strong neodymium magnet separates garnet from all other natural transparent gemstones commonly used in the jewelry trade. Magnetic susceptibility measurements in conjunction with refractive index can be used to distinguish garnet species and varieties, and determine the composition of garnets in terms of percentages of end-member species within an individual gem.

I tried a neodycromium magnet on the slide and it did not appear ot be magnetically attracted – but then I do not know what proportion of this rock is garnet (possibly just the crystals within the matrix) and it is thin, both of which might explain the failure for magnetic attraction.


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First light: Bresser Mikrocam 9.0 on Zeiss IM microscope

I have found out today why this high resolution microscopic camera was so cheap on Astroboot! It only has drivers for Windows XP and Vista – and do what I may I could not get them to work on Windows 7. Therefore, to get it working, I have had to pull out an old Windows XP laptop (from the Ark!) and it does work with this – sometimes you need to hang onto these things and not upgrade everything. It has now become the Bresser Mikrocam computer but does make the camera somewhat bulkier to carry around.

First light images are quite reasonable although some dust I will need to remove later. Initially, I did not work out how to change the white balance so the marble images below all have a blue colouration whereas (once I found the white balance correction button in the software) the Teschenite pictures are far better.

Both marble and Teschenite are from Scotland – 30 micron thin microscopic sections.


Bresser-Mikrocam-9-0-image-Croc-Mor-Marble-221017-x4.bmp (below):

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Bresser-Mikrocam-9-0-image-Croc-Mor-Marble-221017-x40.bmp (below):

Bresser-Mikrocam-9-0-image-Lugar-Ayrshire-Teschenite-221017×4.bmp (below):


Microscopy of microfossils and rock formations from Scarborough

These slides were purchased from SDFossils on ebay Sept 2017.

They compose of a five slide set of thin sections – one is of shelly limestone showing fossils. The others show rock structure – including oolites which look for all the world like fossils but aren’t!

All photos on Zeiss IM microscope with Bresser MikrOkular camera. For this post only x4 and x20 objectives were used.


Shelly Limestone

Shelly Limestone x4 objective – microfossils are seen within the stone

For comparison purposes the following photo is from the Museum of Wales, showing fossils within limestone:


Oolite or oölite (egg stone) is a sedimentary rock formed from ooids, spherical grains composed of concentric layers. The name derives from the Ancient Greek word ??? for egg. Strictly, oolites consist of ooids of diameter 0.25–2 mm; rocks composed of ooids larger than 2 mm are called pisolites. The term oolith can refer to oolite or individual ooids. Some exemplar oolitic limestone, a common term for an oolite, was formed in England during the Jurassic period, and forms the Cotswold Hills, the Isle of Portland, with its famous Portland Stone, and part of the North Yorkshire Moors. A particular type, Bath Stone, gives the buildings of the World Heritage City of Bath their distinctive appearance (Wikipedia).

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Laminated sandstone & mudstone

The following are photographs of microscopy of two laminated rock sections (sandstone and mudstone) from Scarborough.

In geology, lamination is a small scale sequence of fine layers (so called laminae) that occurs in sedimentary rocks. Laminations are normally smaller and less pronounced than bedding. Lamination is often regarded as planar structures one centimetre or less in thickness, whereas bedding layers are greater than one centimetre. However, structures from several millimetres to many centimetres have been described as laminae. A single sedimentary rock can have both laminae and beds. Lamination consists of small differences in the type of sediment that occur throughout the rock. They are caused by cyclic changes in the supply of sediment. These changes can occur in grain size, clay percentage, microfossil content, organic material content or mineral content and often result in pronounced differences in colour between the laminae. Weathering can make the differences even more clear. Lamination can occur as parallel structures (parallel lamination) or in different sets that make an angle with each other (cross-lamination). It can occur in many different types of sedimentary rock, from coarse sandstone to fine shales, mudstones or in evaporites. Lamination is a fine structure and hence it is easily destroyed by bioturbation (the activity of burrowing organisms) shortly after deposition. Lamination therefore survives better under anoxic circumstances, or when the sedimentation rate was high and the sediment was buried before bioturbation could occur. Lamination develops in fine grained sediment when fine grained particles settle, which can only happen in quiet water. Examples of sedimentary environments are deep marine (at the seafloor) or lacustrine (at the bottom of a lake), or mudflats, where the tide creates cyclic differences in sediment supply. Laminations formed in glaciolacustrine environments (in glacier lakes) are a special case. They are called varves. Quaternary varves are used in stratigraphy and palaeoclimatology to reconstruct climate changes during the last few hundred thousand years. Lamination in sandstone is often formed in a coastal environment, where wave energy causes a separation between grains of different sizes (Wikipedia).

Laminated sandstone x4 objective:

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Laminated mudstone x4 objective:

Permian floodplain deposit 260817 with LOMO MNC-1 polarising microscope

I have included three photos using the Bresser MikrOkular camera below from my thin section of Permian floodplain deposit viewed using my LOMO MNC-1 polarising microscope. I can’t see any obvious fossils. Possible fossils from such floodplains were described in an article by Simon et al in the Journal of Sedimentary Research,

A map of the world in the Permian is not as we would think of it today – a large single continent:

My slide comes from Dona Ana County in New Mexico – its location in the USA and the county map is shown below, together with the area’s stratigraphy:



Permian-floodplain-deposit-260817-0-6x-intermed-lens.bmp (below):

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Permian-floodplain-deposit-260817- 7x-intermed-lens.bmp (below):