Argillite with Mud Cracks Identified

This video identifies the sedimentary rock argillite using 360 degree photography.
This argillite contains filled mud cracks and salt mold structures.
Argillite is similar to shale--were muds and clays become deposited in low energy environments such as on lake bottoms swamps and also ocean bottoms.
However argillite tends to be more massive individual layers have few natural divisions in structure than shale.
Argillite generally doesnt split easily along bedding layers compared to shale.
Note that argillite can be borderline metamorphic. Argillite usually has a gray- or- black color.
However shale can have a light brown tan red or nearly white color too.
In general it is a siltstone or mudstone made of pulverized rock particlessediment that are between 132 of a millimeter to- 1256 of a millimeter in diameter but also can contain particlessediments that are less than 1256 of a millimeter in diameter.
Both silt and clay are too small to differentiate without a microscope in a lab.
This sample was collected on a Northwest Geological Society field trip in the late 1990s.
I believe it was collected in Northern Idaho.
This sample seems similar to argillites in the Rocky Mountains Belt Supergroup--but Im not certain because it was collected long ago.
Ill need to look at the field trip guidebook to confirm information.
I will make changes to these notes--if necessary.
This sample contains cubic molds--which are the dissolved remnants of halite crystals salt.
This implies the depositional environment was a playa lake or evaporative lake bed.
Unfortunately these cubic features are not very clear within the 360-degree video spin.
However I have included a photograph with low-angle lighting to highlight some of the cubic surface features. Hello Rock People! This is Dave the Geology Dude.
Note that I have other videos with more rock identification information on my YouTube channel.
It is best to see as many examples of the same rock type--because only then you understand the range of variables associated with each rock type.
Also be aware that the only way to really learn rock identification is to have hands-on experience.
This is because visual experiences alone do not show the physical properties like hardness acid reactivity and the range of variables that are common to each rock type.
Dont forget that: Geology isnt Rocket Science--its Rock Science! Please like and subscribe to this YouTube channel! Identification information for this rock: 1 environment: low-energy environments ponded water is not moving--a bottom of a pond swamp lake or ocean. 2 color--usually dark gray or black although light brownish colors are possible to such as this example 3 acid reactivity: generally will not react to acid unless it was deposited into salt water 4 luster--earthy and dull.
5 other characteristics--because shale often contains clay the rock will lightly attach or stick to your tongue.
That is why shale is considered a tongue-grabber like kaolinite clay minerals.
This sample does not appear to contain much clay not a tongue-grabber 6 often confused with shale or slate.
See notes above for explanation. Music YouTube Audio Library: Longer Distance by TrackTribe Copyright by David Knoblach 2023.
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Источник: rutube.ru