During my trip on the river Elbe (see also my article from yesterday) I found some pieces of material which immediatelly got my attention: a kind of metamorphic “object” that looked almost like a… meteorite (photo width – 40 mm):

There was not only one but 8 such things on about 5 m² area and because they all looked at least weird to me, I took some samples with me at home (sizes between 1 – 5 cm). As to my knowledge, there was no active volcano in the region and recent meteoric activity can be excluded too since no reports have been recorded in this area. However, 3 out of 8 pieces contain certain amount of iron confirmed by their magnetic properties, which makes the meteoric origin at least plausible. The photo below is about 18 mm wide:

If this is indeed of meteoric or volcanic origin, than the river may have transported the little objectes from really far away in the montaneous area. Two plausible explanations may support or deny this theory: 1) these are not stones but slug fragments of smelted metal ore from the nearby mountains (but how did it get into the river?) and 2) the fragments represent some slags from either the boats’ traffic on the river or construction works. Second option seems to be the most plausible, given also the fact that the collecting site was located in the immediate vicinity of a major street.

Today we had a great sunny day out in the nature. Together with our friends we’ve been rowing on the Elbe River on pneumatic boats between Bad Schandau and Kurort Rathen (only about 15 km but full of fun). As we were waiting for the boats to be delivered we stopped on the river banks and had a quick barbeque. I used the chance and looked for some interesting stones.

Of course I did not forget to take a small sand sample for my Sand Atlas. This will be later added to my sub-project “Sands of the Elbe River”, a characterisation of the river sediments from the source to estuary. Even if the sand is not extraordinary in regard to its origin or texture, I feel happy with every single new sample added to my collection.

Among the stones collected, especially one has got my attention: a dark, well rounded stone of about 4 cm with lamelar basaltic intrusions in a crystaline mass (the photo above is 8 mm wide). I can only try to imagine what kind of forces got all those elements together over the millions of years of existence.

After so much geology in my previous posts it has been time for little travel. We went out today into nature and drove to Bielatal, a nice region belonging to Sächsische Schweiz (sandstone region near Dresden close to the Czech border). The trekking tour started in Rosenthal (parking lot “Altes Zollhaus”) and we were heading south toward Czech border, then along the border up to Fuchsteich” and then back to Rosenthal. For those not familiar with the area the names say nothing but this website is about sand so here comes the sand story:

On the way back to Dresden we stopped at the spot called “Labyrinth”, a heavy whethered rock formation which can be visited by just walking one km from the main road. The area is made of huge sandstone blocks randomly arranged and welcoming especially the kinds for a funny walk around them.

The rocks are very eroded and in some places they reveal the original sandstone colors: from grey to orange and reddish, all typical colors for Sächsische Schweiz sandstone formations.

Yes, that kind of mineral exists in nature under the name fuchsite and it is just a colored form of the common mica found in some sands (original name: muscovite). The gree mica is actually a variety of muscovite very reach in chromium (usually between 1-5%). While the common mica is grey or silver, the fuchsite form has a very nice, bright green color.

The photo above is of a little stone gathered from a stone carving artist from northern Germany who opened a galery with artistic gardening ideas (photo wide: 8 mm). One of them included fuchsite as main element due to its warm color. When the stone is exposed to sunset light it shines even stronger than under normal light, which makes the stone very attractive for colored garden fans.

Almandine is a rock-forming mineral with a deep red color (slightly purple) belonging to the garnet group. Chemically, almandine is a iron-alluminium garnet with the formula Fe₃Al₂(SiO₄)₃.

The name almandine (also known as carbuncle) comes from Alabanda, a region in Asia where the minerals were firstly found in ancient times. The term carbuncle is derived from latin and means “live coal” or burning charcoal. Almandine occurs frequently in metamorphic rocks like mica schists, similar as in the photo above taken from a small piece of conglomerate found on a beach at Baltic Sea.

Fascinated by the photographs in the previous post I searched for more stones in our small stone rack and the results we can see below. Again I don’t know much about their composition but when I’ll know more I’ll update this post so you shall come back later and check this entry.

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Yesterday we’ve been walking on the shores of a small lake not far from our house and brought back home a couple of stones. They were just regular stones but after braking them they revealed a nice texture which I though I’d share with you. Even if I know almost nothing about their composition or constituent minerals, I like very much how they look in front of the lens. All photos are 10 mm wide.

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Walking a few days ago on the beach in Vung Tau (South Vietnam) it just happened to walk by a stack of small sand balls which just laid down on the beach in front of me. Looking more carefully I had noticed that next to each agglomeration of sand droplets there is a small hole and after waiting a few minutes, some tiny creature has shown up and gave me a smile.

This was the famous sand crab which burrows holes in the sand and feds itself with phytoplankton and small organic debris brought by the waves to the beach. The eating procedure consists in just catching the organic particles with their tentackles, most of them already present between the sand grains. The crabs are of different sizes growing up to 35 mm long and 25 mm wide, building nice sand patterns on the beach:

Sand crabs are used as bait by fishermen. Some sand crabs are also used by humans to monitor the concentrations of domoic acid in water, a toxin produced by a type of phytoplankton. When sand crabs eat the toxic substance, they become toxic for the birds and fishes that consume them. By measuring the concentration of domoic acid in crabs’ flesh one can estimate the toxin level in the water. The sand crabs reproduce by eggs (about 45.000) which are carried by the female crab on her abdomen for about 30 days.

Some more info on sand crabs, also known as mole crabs:

• digging kinematics (legs coordination) of sand crabs: Faulkes and Paul, 1997
• description, natural history and monitoring of Pacific mole crabs

Namibia – Erongo – 80 km E of Swakopmund (Langer Heinrich open pit uranium mine)

Sample from an open pit uranium mine. There are two types of minerals inside, both of green color. While the one on the bottom-left may be serpentine, I guess the big grain in the middle is malachite.

Yesterday I have received from a trade partner a series of nice sands from Austria, mostly areas around Salzburg and Tirol. The sands are from mountain and, as it was written on the bags, they contain a mixture of quartz, gneis, mica, feldspat and some other elements. The sand has a nice metalic shining under direct light. I have photographed only the sample 1595 AT-SZ but there are some more similar samples to follow (see also the photo gallery).