Question: Is that pyrite crystals in this piece of oil shale? I picked it up on the beach on my last trip. Or is it some strange fossil? Whatever it is, why/how/when do they form like this in the shale?

In my collection of “things and stuff” I got one really nice object that usually makes people envious. It’s a shaft hole axe from Uppland in Sweden. It was my grandfather who in his youth found it on a field. The archaeological dating sets this axe to the middle or late Neolithic. Around 3000 BC perhaps. But I’m not sure on that, it’s been a while since I took archaeology and the making of shaft hole axes streches some time.

Geology-wise this axe is made of, what I think at least, some form of ordinary diabase. The weight, the archaeological practise of using diabase, it all tells me this at least. There’s no volcanoes in or near Uppland (which basically is mostly old igneous bedrock, granites at about 1800 Ma), so I dont think its basalt, but rather diabase. It could be imported/transported of course. But theres a lot of shaft hole axes found in Uppland so I dont think so.

At first, the axe was all nice and shiny black in colour, with some hints of olivine green even. But then I decided to wash it and under a thick layer of like 70 years of handling and showing to people (sounds better than 70 years of deposited human dirts and fats) and that revealed a more grayish dull stone with a hint of green tones. Theres also some redish spots that came out from under the filth which looks like rust almost. I’m not so sure any more of what this stone is made of in detail since no crystalline structure is visible because of the grinding and smoothing of the axe. Any suggestions? My guess is diabase and that the small cracks and holes are the result of erosion of more fragile plagioclase in a resistant matrix of augite and olivine.

Anyhow, depending how you look at it, its an 5000 year old axe or a 1800 million year old pice of rock. And its all mine, my sweet precious shaft hole axe… 

I’ve been saving this rock for a later post. But complications have made it impossible for me to examine the rock up close any time soon. All I have are these older photos below. So I can just write about it now I guess, it wont matter if I wait any longer.

It’s (supposedly) not magnetic (that rules out iron slag right?). It (supposedly) weighs about 1-2 kilos. Its about 15x10x10 cm in size. (reduced size on the photos)

I sent the photos to an geology expert a couple of years ago, before studying geology myself in the hopes of helping my (now sadly enough dead) friend in helping to identify it.

The expert just replied shortly and claimed that it “most definitely was a conglomerate”.

Im no expert, just a first year student. An amateur. But this doesn’t look like any conglomerate that I know of. Where are the pieces of rocks and granules? Shouldn’t there be at least one lousy piece of granule visible if the craters are the sockets of rocks? Are they really all loosened and gone? Doesnt sound very plaucible to me. And when I replied to the experts answer with a follow up queastion and asked how this could be a conglomerate without any visible captured parts, his stuck up pride probably got offended and he just got bored with me and didnt answer at all. I almost lost all faith in geologists that time. What an idiot. Esteemed professor emeritus of Lund university and all. Well, he didnt make that far in the academical world on being friendly to the taxpayers who payed him and his research (Publically funded universities in Sweden you know). Well enough about him.

In my, very unprofessional opinion, this looks much more like a meteorite. But according to the expert, that wasnt even an option. I really never understood why.

I know that meteorites of course are less likely to be found in comparison to just about any type of rock. I’m not stupid on that part. But I can’t get over the fact that it looks like one much more than it looks like a conglomerate.  

The rock also comes with a story (from my dead friend) that his father actually saw “a falling star” and went looking in the direction of where it seemed to have fell. Some miles away he found burned grass and this piece of rock between some cliffs at the west coast of Sweden. Around 1920 I think he said this all took place.

What does my readers say? Conglomerate? Meteorite? Iron slag? Flint? Or something else? What can you make of it just by looking at these photos (that’s all I have, its impossible for me to examine the rock itself or take better photos any time soon). Im all ears.

Got a new camera. Nothing fancy, a "Canon digital Ixus 950 is". But it had a nice macro-function so i took som new photos just for fun.

Picture below is a garnet crystal inside of a amfibolitic rock. Hornblende to be precise. Picked it up on an excursion.

Picture below is of a olivine crystal (or a couple of them of course) inside a basalt rock from a small dead "vulcano" in the middle of Scania. Age about 145 Ma. Picked it up on an excursion.

Picture below is of an ordinary sandstone heavily oxidized with iron found in an Jurassic-Trias-deposit of sand. Its composed of several layers of differently oxidized and dense sediments. Looks more strange than it is. 

The picture below is not totaly geological but still quite nice. A piece of iron slag from Uppåkra (Uppakra) Iron age settlement outside Lund (roughly 700 AD perhaps). Since I started my career with archaeology I also have some archaeological things in my possesions. Some of them I actually found myself on field training exercises like this slag and the piece of pottery below.

The picture below is of a piece of Iron age pottery from the same settlement/village.  

Today, in the lovely spring weather we have here in the south of Sweden, I took a small trip out to the nature reserve called Billebjer just outside my town of Lund. It’s part of the horst that is called Rommeleaasen, a horst that is part of a greater geological system called Tornqvist zone. Basically the Tornqvist zone is a lot of ancient faults stretching from the Black Sea to somewhere outside Scotland. This zone begun to form some 300 million years ago and the horsts was raised some 60 million years ago.

Most of the rocks are difficult to identify by visual means since the bedrock is covered with growth and heavily cracked and eroded. And fresh surfaces of bedrock only reveal a diffuse rusty rock. But looking at the bedrock up close revealed more typical traits of a granite. And small traces of a metamorphic process could also be seen. But I was far from sure so I had to cheat and look it up at the webpage of the Swedish geological survey. According to them it’s a Orthogneiss. But Im not completely convinced and some pages on the internet talk about a granite-gneiss. That is, a only slightly metamorfed granite. But other sources talked about an Amphibolite rock that also is common in this horst. Well, my guess is a very iron rich granite-gneiss perhaps. Its so full of this "rust" that its almost impossible to see what it is. It almost looks like a sedimentary rock at a distance. But that much I know, it isnt.

Igneous bedrocks are not the dominate bedrock in the very south of Sweden (where I live). Most of the bedrock here is sedimentary and the metamorfed or igneous rocks are hidden deep below or only revealed through horsts. The Billebjer formation is one of few spots where I can look at the bedrock in close vicinity of Lund. North of the Tornqvist zone the igneous bedrock becomes more and more common. And basically 90% av the Swedish topside bedrock is metamorfic or igneous. The province of Scania (Skåne) where I live and the island of Gotland are the exceptions and especially here in Scania you can find all sorts of bedrock. From 2 billion year old igneous rocks to tetriary sedimentary deposits.

I have two pieces of rock which I cannot identify for sure since Im quite new at geology. I would like your opinions of them and what you know or think. I have no instruments at home so the photos is basically what you get. If you aren’t sure, an educated guess is better than nothing.

Rock A

Found on the island of Gotland (as you now know have a primarily Silurian lime stone bedrock). Def. sedimentary. Perhaps a conglomerate of some sort? White circular or oval granules surrounded by grey filling. The white filling however looks a bit precipitated almost. And the white granules seems to erode more quicker than the surrounding area. Also a couple of charcoal-looking black crystals (but a lot harder than ordinary coal. Perhaps a hornblende?) embed inside some of the white granules. No certain trace of any distinct macro fossils. Low density/weight.

Rock B

A rock with heavy density and large milkywhite plagioclase-looking crystals (they look more transparent on the closeup picture than in reality so ignore the transparent effect on the close up) embedded in a black igneous rock. No traces of quartz what I can see. There are also a few random red granules or "holes". Found on the Swedish mainland so it could very well have come from anywhere due to the ice age.

This is my first post on the blog and I bid you welcome. I hope to use this blog frequently to share with you thoughts on the geosciences with focus on geology.

But other topics might arise like the climate, archaeology, politics, religion, philosophy and science fiction. I am a geek of the hominid type, and I am here to preach the Gospels of my entire geosphere. This blog will therefor combine both science and philosophy and I will try to make geology as fun and exciting for you as it already is for me. And by writing blog posts I will of course help my self in my studies by forcing myself to explore the facts before writing. That means this blog isnt just for you.

Please use the navigator menus above to explain any questions you might have about the basics. If you cant find it there then Wikipedia as an excellent collection of articles in the fields of geoscience. And please excuse my English since I am from Sweden, English isnt my primary language. Grammar and spelling might become "strange" at times. My geographical location will also limit most of my posts on geology to the geology of Sweden. But fear not ye easily bored - Sweden has everything from vulcanos to dinosaurs. The Earth is both big and more than 4500 million years old, so I doubt that I will run out of topics any time soon.

The picture below is the beautiful Giant’s Causeway in Ireland. They consist of over 40 000 basalt columns. Their age is somewhere in the Paleogene period. (That is between 65 and 23 millions years ago.). Basalt columns are formed when basalt (a lava flow) cools of  and contracts and forms cooling joints due to the contraction when the rock cracks (cold matter contracts compared to warm). The shape is simply caused by the effect this form (hexagonal in this case) being the most simple and easy solution for the rock to crack under contractive stress due to the jointing rules of that perticular rock (basalt). It is not a cristalline effect like one might think. But it sure looks strange. The basalt is highly resistant to erosion and therefor the shapes can be seen for millions of years. But one day it will become complety eroded.