Common Metamorphic Rocks Identified
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- čas přidán 6. 10. 2022
- This is a quick look at many different metamorphic rock samples. Note that I have many other individual videos on these rock types (look for them in the channel video listings, for more information). There are many types of metamorphic rocks. There are some metamorphic minerals too. But the most common metamorphic rocks are in this video.
There are only six metamorphic rocks on this list: slate, phyllite, schist, gneiss, marble, and quartzite. These rocks can come in a variety of colors. The rocks also can have structures that are either layered (foliated), or not layered (unfoliated). Some rocks, like marble and quartzite, can look very similar to each other (but marble reacts to acid contact and quartzite does not). Also, phyllite often looks a lot like slate, and schist often looks a lot like gneiss. So these pictures quickly show some obvious differences and similarities. But the pictures also demonstrate that just looking at a rock often is not enough to identify it. Performing tests to identify characteristics are often necessary.
Again, I have covered these rocks in more detail in other videos on GeologyDude. These other videos use 360 degree photography, to create a three dimensional-like view effect. My initial focus on this channel is to provide a variety of ways to learn about rock identification. I will gradually expand into other topics, but I feel that learning about rocks is one of the key things I want to cover first.
Hello Rock People! This is Dave the Geology Dude. Please 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 properties like hardness, acid reactivity, and the range of variables that are common to each rock type. Don't forget that: Geology isn't Rocket Science--it's Rock Science! Please "like" and subscribe to this CZcams channel!
General identification information:
1) Rock identification is first a visual thing, but various tests on the rock sample are often needed to confirm characteristics. The first thing is to be aware that some rocks come in multiple colors and can look very similar to other rock types. So don't focus on identification by using only color. You will make mistakes by using only color, and it is relatively simple to learn a few ways to determine characteristics to become much more accurate.
2) The more types of the same rock that you see, the better you will get at knowing the parameters of each rock type. Repetition and looking at many rock samples will make it easier for identification. You need this to understand nuances better, and what really to focus on for certain characteristics.
3) If you are looking at all rock types, know the general ways to identify each rock category of igneous, sedimentary, and metamorphic. After identifying the general rock category, then you can go for the tests to determine the rock type you have.
4) Most rock types have only one- to- three key characteristics that will allow identification. There are many types of characteristics, and you need to know them. But don't be overwhelmed. Eventually you will be able to look at a rock and know probably what it is before you even touch the rock. However, you need to confirm your hunch--by trying a hardness test, acid reaction test, etc.
5) Based on #4 (above), you need to perform these key tests to confirm the characteristics of the rock sample. It is easy to be tricked at times, so don't get lazy and skip a test on an important characteristic. For example: A) You must try the acid reaction test, to see if the rock chemically reacts; B) You must try the hardness test to see if it scratches glass. You must perform these tests to really know the result.
6) You need to identify other characteristics too, such as grain size, types of minerals in the rock, and structures in the rock (such as foliation). All these features may not be always clear, but by compiling a survey of the characteristics, you have more information to make a correct identification.
Other information:
Marble: this will react to acid contact (small bubbles will effervesce like a soda or fizzy drink). It may have any color and may be either foliated or unfoliated (no layers, or with layers)
Quartzite: this will scratch glass and may be either foliated or unfoliated
Slate: will look barely reflective like an old black board
Phyllite: will look slight more reflective than slate--with a slightly silky surface
Schist: will have visible muscovite or biotite and will sparkle like sequins on a dress. May contain garnets
Gneiss: will not have muscovite or biotite but will be foliated (layered)
Music (CZcams Audio Library): Music: Read All Over (by Nathan Moore)
Copyright by David Knoblach, 2022. All rights reserved
Hello Rock People! This is Dave the Geology Dude! There is more to this video than just quick views of rocks. There are detailed notes in the description area for this video. If you want more, longer length videos are on my CZcams homepage. Check them out, or leave a comment here!
Really think you very much.can you visit India for help us?
@@narendramakwana8429 I sincerely thank you for enjoying my videos and thinking so highly of my content. I rarely leave the United States, and because of a job injury many years ago, I have focused more on geology education instead of doing consulting work. Also, my specialty is in non-metallic minerals…. I plan to have many future videos that have much more detailed information than rotating rocks. But for now, I want to finish this series of short videos on the the most common rock types. Using the visual effects of photogrammetry, I think it is the best way to create a basic resource for people interested in rocks. Again thank you very much for your kind words.
Ahh my favorite rock class, the metamorphics . So
Much magic happens here, I love it! Do you happen to have any amphibolites hiding anywhere in your collection dave?
I have a good amphibolite, and will look for it. But first I need to finish the photogrammetry of 3-5 more common minerals-so I can complete this series on various rock types. Fall geology classes have started, and these survey videos are a great way to let people know about all the videos I made during this past summer.
@@GeologyDude sweet! No rush Dave , do your thing . Earlier this year I found a tiny spot on the river that has some really good amphibolites and also some really beautiful gneisses. My favorite so far was a 127 lb garnet amphibolite . I got a hernia grabbing it but was well worth it 😆
@@mafic_taco7061 at first I thought you wrote “a 127 lbs garnet” ha ha. Well, big samples are always the best samples.
May We get gold from it??
Interesting question! Yes, gold is found in igneous, sedimentary and also metamorphic rocks. Marble, slate, argillite (a type of slate), phyllite, schist, gneiss, and quartzite can contain gold. Generally the amounts of gold are slightly lower in metamorphic rocks compared to the other rock types. Although the report I looked at for this answer, analyzed fewer metamorphic rocks than other rock types. Of course the local environmental conditions are key importance as to where gold forms in rocks.