lab 1 report 1 4 5 6
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CUNY Hunter College *
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10000
Subject
Geology
Date
Jan 9, 2024
Type
Pages
3
Uploaded by CaptainGrouseMaster1014
1
Title: Report of Igneous, Sedimentary, and Metamorphic Rocks
To begin this report, we first must dive deep into the actual lab itself. The fifth lab that was conducted
was specifically about the identification of igneous, sedimentary, and metamorphic rocks. The lab
required that I gather rock samples from these rock groups and identify them based on the different
properties that each rock sample shows. An example would be I identified the texture that the igneous
rock samples showed in my first step and continued with identifying different properties with the rest of
the rock samples. The main focus is going to be the identification of rocks and the methods of how we
identify these rocks. For my Igneous Rock samples, I was tasked to find the texture, color, and magma
type (was unclear to me at the time so I was unable to identify the correct magma types). I was able to
correctly identify the first two properties but since I was unclear with the magma type it would make it
that much harder to find the correct rock type. Igneous rocks can vary widely in color, ranging from light
to dark. Sorting the samples from light to dark colors allowed me to make initial categorizations,
although I later realized that the specific magma type could provide more definitive identifications. By
looking at and feeling the texture, I was able to see whether a sample had a fine-grained, medium-
grained, or coarse-grained texture. This provided valuable insights into the rock's cooling history and
mineral composition. For my Sedimentary rock samples, I was tasked to find the texture again which
refers to either clastic, chemical, biochemical, or organic, the grain size, and the examination of clasts. I
began the identification process by closely examining the texture of each rock sample. This helped me
differentiate between the primary categories of sedimentary rocks: clastic, chemical, biochemical, and
organic. Observing grain size was essential to making accurate classifications within the clastic category.
The presence of clasts in clastic rocks was another valuable indicator. I paid close attention to whether
clasts were rounded or angular. For my Metamorphic rock samples, I was tasked to find the
texture(foliation), Foliated rocks exhibit a layered or banded texture, whereas non-foliated rocks appear
more uniform. As well as the specific texture of each sample. Minerals had a slight part in some of my
identifications of these rock samples as well, therefore, a combination of visual observation, physical
properties, and laboratory analyses may be necessary for accurate identification of these rock samples.
For my Igneous rock samples, the specific properties I saw were color and texture, I was not able to
identify the correct magma types. I concluded that the samples I3, I5, and I6, were all phaneritic
textures, and the colors were I3 is Dark, I5 is Intermediate, and I6 is Light. I couldn’t identify these
samples correctly since I didn’t know the magma type due to a misunderstanding. I guessed that I3 was
Granite, I5 was Diorite, and I6 was Gabbro which wasn’t correct. I then did the same for ro
ck samples I-
1, I-2, I-4. I identified I-1 as porphyritic, I2 is aphanitic, and I-4 as porphyritic. I-4 was incorrect. I then
identified the rocks as Andesite, rhyolite, and basalt which were all correct. For my sedimentary rock
samples, the specific properties I saw were identifying the subcategory, the texture (course-grained fine-
grained, etc.), and the clasts. S3, S5, S6, S7 were all clastic. S7 is fine-grained. S3 is medium-grained. S6
and S5 are both coarse-grained. I identified S5 as rounded clasts and S6 as angular. I was able to
successfully identify the rocks because I correctly identified the necessary properties, unlike my igneous
rock samples. S3 is sandstone, S5 is conglomerate, S6 is breccia and S7 is shale. I then identified S1 as a
chemical which is incorrect it is biochemical. I then was tasked to find the mineral type in S1 which was
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calcite. For my metamorphic rock samples, I had to identify the correct foliation category which was
foliated for these rock samples. I was also tasked to find the textures for the rocks which although I
didn’t use the proper wording for texture for these metamorphic rock types in my lab, M
-1 slaty (very
fine) M-2 phyletic(fine), M-3 schistose and M-4 gneissic (med to coarse grained) I had gotten the gist of
the textures of the samples and was able to correctly identify the rock samples. The rocks were M-1
Slate, M-2 Phyllite, M-3 Schist, M-4 Gneiss. I then was tasked to find M-5 and M-6 foliation categories
(non-foliated for both). I identified M-5 and M-6 as coarse-grained but M-5 is fine-grained. I identified
the minerals in these rock samples as well, m5 is quartz, M6 is calcite. Due to a little misunderstanding
and not being able to do the acid test at the time, I didn’t identify these samples, but they are M
-5
Quartzite and M-6 Marble. For the igneous rock samples, the properties examined for rock identification
varied in their difficulty. In the case of igneous rocks, color, and texture were essential properties, but
the misunderstanding I had about magma types posed a significant challenge in being able to identify
the correct types proven by my incorrect attempt. Texture played a vital role in distinguishing between
the samples, and it was critical in correctly identifying some of the rocks. Once the correct sub-
categories were understood, it was easier to make accurate identifications. Overall, without the magma
types identified, it was hard to identify the correct rocks. For sedimentary rocks, identifying the sub-
category proved to be a highly valuable property, as it led to the correct classification of rocks as clastic.
Texture, including grain size, was also essential. The size of clasts (fragments) in clastic sedimentary
rocks is a prominent feature. This size difference is often very visible to the naked eye and wasn’t hard
for me. The presence of rounded or angular clasts was particularly useful for distinguishing certain rock
types, especially conglomerate, and breccia. The texture and sub-category were critical for
differentiating these rocks. I was able to easily identify the properties of sedimentary rocks and it is
reflected in my lab as I can identify all the rock samples in the sedimentary rock category correctly. In
the case of metamorphic rocks, the foliation category was a pretty easy-to-identify property and proven
as I correctly identified the samples as foliated or non-foliated. The parallel arrangement is easy to tell
by the naked eye in my opinion. Texture was also significant, although it was a little challenging due to
the variety in grain size descriptions and honestly, I second guess myself a lot whenever I’m feeling
things or even looking but I still pushed through. The mineral composition of the metamorphic rocks was
vital for specific identifications, and the presence of minerals like calcite and quartz played a central
role. The level of difficulty wasn’t too high though compar
ed to my igneous rock samples as in this part
of the lab as well I was able to correctly identify the rock samples. In conclusion, we explored the world
of rocks, focusing on igneous, sedimentary, and metamorphic categories. When identifying igneous
rocks, we relied heavily on texture and color, but the absence of magma-type knowledge led to
inaccuracies in our identifications. The specific sub-categories like phaneritic and more provided the
needed details for successful identification. For sedimentary rocks, properties like sub-categories,
texture, and clasts were crucial. Successfully determining the sub-category helped distinguish between
clastic, chemical, and biochemical rocks. Texture and clast nature (rounded or angular) further enabled
accurate identification. For metamorphic rocks, finding foliation categories, texture, and mineral
composition. Foliation served as a reliable identifier, and mineral composition as well as texture. In
summary, this lab showed the importance of properties like texture, sub-categories, foliation, and
mineral composition in rock identification. It also highlighted the challenges that can arise when certain
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properties remain unclear, emphasizing the need for more information to make precise identifications.
This experience deepened my geological knowledge and honed my skills in rock identification
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