15
votes
Accepted
What kind of rock is this being eaten by a rock-eating worm?
thank you for your interest in the article. I'm the lead author on this paper (Shipway) and I happened to come across your post when looking through all the media stories on this animal.
To answer ...
- 166
8
votes
What's the diference between claystone, silt, mud, mudstone, mudrock, clay, shale and siltstone?
Clastic sedimentary rocks are classified by size of the sediment particles making up the rock. Particle size descriptions like sand, silt, and clay have specific meaning in geology and engineering. (...
- 5,959
7
votes
Do you have any informations about fossil-rich cherts from Scandinavia?
What you are looking for is information about the "Oslofeltet" (Oslo-field) in Norway (dated to be from the Ordovicium period, 443 - 488 million years old). This is a concentrated field of of fossils. ...
- 1,886
7
votes
How do quartz veins form?
The formation of quartz veins needs fluids enriched in Si. Usually Si dissolves somewhere in neighbouring formations, gets transported by fluids and precipitates where the fluid pressure is low (the ...
- 231
7
votes
Are we observing sedimentary rock formation today?
The transformation of sand into sandstone per se cannot be directly witnessed, as it's happening deep in the earth. However, there are types of cementation that happen quickly and in plain view:
A ...
- 3,628
6
votes
Accepted
How did the terms "acidic" and "basic" come to be associated with $SiO_2$ in igneous rocks?
The idea came from the theory that silicic acid was the chief form of silicon occurring in rocks. Early attempts to classify minerals, placed some mineral specimens in groups based acid-base ...
- 5,959
6
votes
There are cloud identification guides, are there also (guided) rock identification websites?
I looked through your step-by-step cloud identification guides, and they seem pretty easy. The overwhelming criterion for which cloud it is is "how does it look", with the addition of the obvious "is ...
- 23.1k
6
votes
Crystallization path of diopside-wollastonite-silica systems
The diopside–wollastonite–silica system ($\ce{CaMgSi2O6-CaSiO3-SiO2}$) was never studied for crystallisation paths in igneous systems. This is not a system encountered in terrestrial magmas, so no one ...
- 23.1k
6
votes
Accepted
Can serpentinite come from basalt?
Serpentine can form in basalt, but it is likely to be less extensive than in some other mafic rocks such as dunite or harzburgite.
Serpentinization is primarily associated with the minerals olivine ...
- 4,041
5
votes
Accepted
What is meant by intraplate volcanism?
The majority of Earth's volcanoes occur in plate boundaries. These can be at spreading ridges (green dots on the map) where they are mostly underwater, but sometimes are above the water (such as in ...
- 23.1k
5
votes
What is meant by intraplate volcanism?
Terms:
Intraplate volcanism - as the name suggests it is volcanism within the plates rather than at plate boundaries.
These are also known as hotspots.
Ocean island basalt (OIB) - is the basaltic ...
- 133
5
votes
Please help in understanding redox buffers
First let me start by saying that redox buffers are a made-up thing. All these QFM (actually FMQ) or NNO or other abbreviations don't exist in nature. They were developed as a way to "cheat" in ...
- 23.1k
5
votes
Accepted
In an Earth-like planet with no history of carbon-based life forms, would there be limestone?
I'd have to say, yes. Once life evolved in the world's oceans, the vast majority of limestone formation has been through the organic process. However, before life did evolve, limestone formed through ...
- 2,187
5
votes
Accepted
How did this stone become encased within different rock?
it was simply an older stone smoothed by water that had fallen into sediment.
This is exactly what happened. There's a name for that: a conglomerate.
- 23.1k
4
votes
Why do gold deposits form only in certain areas of the earth?
I do agree with Gimelist how gold is accumulated through hydrothermal fluids, adding that the main driver is for this process is volcanism.
There is, however, something interesting to be noted. We ...
- 41
4
votes
Accepted
How can I tell the difference between granite and syenite?
It is confusing - both rocks are commonly pink overall. But, granite has abundant quartz, syenite has no quartz to very little. Quartz will be the grey translucent mineral that looks just like a blob ...
- 23.1k
4
votes
Accepted
Can cooled/hardened lava rock return to a molten state?
Yes, at least partially.
It is important to remember that a "rock" usually does not have a single melting point. It melts over an interval. Igneous (magmatic) rocks are made of combination of ...
- 23.1k
4
votes
Identification of limestone type
Limestones are usually categorized following the Dunham & Folk classification. Only very rare or special limestones were given a name and these are often named after the location where they can be ...
- 109
4
votes
What determines the scale of columnar jointing?
There is a paper about this in the Bulletin of Volcanology (Hetényi et al. 2012).
Cooling rate seems to be the main parameter controlling column size (faster cooling yielding to thinner columns). ...
- 8,141
4
votes
Accepted
On QAPF (Steckeisen) diagrams, should Albite be considered on the Alkali feldspar or Plagioclase side? Or in-between?
When it comes to igneous rocks classification, the bible is Igneous Rocks: A Classification and Glossary of Terms (Le Maitre et al., 2002). It says (p.4):
A = alkali feldspar, including orthoclase, ...
- 8,141
4
votes
Accepted
Why was quartz not a major product of the Lunar Magma Ocean?
Fractional crystallization indeed makes magmas more silicic. However, you'll never reach a magma composition with 100 % silica, which could then cool and crystallize as quartz. The starting material (...
- 8,141
3
votes
In an Earth-like planet with no history of carbon-based life forms, would there be limestone?
In an Earth-like planet with no history of carbon-based life forms, would there be limestone?
Short answer: Maybe.
The form of carbon in limestone is oxidised carbon: carbonate: CO32-. This is ...
- 23.1k
3
votes
How do quartz veins form?
Quarz veins come in different sizes - starting from milimetre scale ending with several meters (if not more). Quartz veins form from aqueous solution and in most cases that is associated with high ...
- 549
3
votes
Where can I get mineral testing done?
It depends on what type of test. If you just want simple identification this site offers a tentative one and any museum with a mineralogy section will have someone on staff who can do identification ...
- 7,026
3
votes
Accepted
How this sedimentary rock is made?
The rock you show is a conglomerate - it contains a substantial amount of clasts (your pieces) that are gravel or larger size. The pieces have been cemented together into a new rock - kind of like ...
- 4,419
3
votes
Does ground-to-cloud lightning create crystals as well?
I would assume that any lightning bolt connecting to the ground would be capable of producing a fulgerite in the soil, regardless of the direction that the bolt "flows". Fulgerites are caused by the ...
- 94
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