Granulite: Laf 109
Item
-
Title
-
Granulite: Laf 109
-
Description
-
Type: Metamorphic Rock
Minerals Present: Garnet, Hornblende, Biotite, Plagioclase Feldspar, Quartz, Potassium Feldspar, Magnetite/ Ilmenite
This sample is classified as a granulite, because it shows no clear examples of foliation. The rock can be divided into two separate areas with very different characteristics. In hand sample the color is generally brown. Garnet and hornblende crystals can be seen with the naked eye.
The thin section made of this sample captures both areas of the specimen. Both halves are is porphyroblastic, but differ in mineral assemblages. One half contains large porphyroblasts of almadine garnets with many inclusions. The fine-grained minerals surrounding the garnet consist of mostly quartz and potassium feldspars. The garnets have an idioblastic shape, meaning that their crystal faces are well formed. Another prominent mineral seen within the thin section is a black, bladed, opaque mineral, possibly magnetite or Ilmenite. The other half of the hand sample consists of large, elongate hornblende and biotite porphyroblasts surrounded by smaller grains of garnets, plagioclase feldspar, and magnetite/Ilmenite. The hornblende and biotite crystals are all oriented parallel to one another, suggesting foliation. Its possible that this section of the rock is classified as an amphibolite, due to the lineation seen in thin section. How these two facies came to be in such close proximity is a mystery.
-
Creator
-
4737
-
Type
-
Metamorphic Rock
-
Mediator
-
Tamara Carley
https://exhibits.lafayette.edu/geology/files/original/fc773f875195a0d7d7dcaa462ac0231c.jpeg
https://exhibits.lafayette.edu/geology/files/original/937dd39715331ed661a20b05dc74ffd4.jpeg
https://exhibits.lafayette.edu/geology/files/original/67b10ae6a99f95d2375f13ad91abb2b7.jpeg
https://exhibits.lafayette.edu/geology/files/original/c0f60ae1b06ddf507160bdf2483df34c.jpeg
https://exhibits.lafayette.edu/geology/files/original/1adbc90058f7cf577c40579d0fe47044.jpeg
https://exhibits.lafayette.edu/geology/files/original/3d156f2aeec2517f097df71cb218946e.jpeg
https://exhibits.lafayette.edu/geology/files/original/815cfaa1a6f606752af6f94d466f51d6.jpeg
https://exhibits.lafayette.edu/geology/files/original/de3029309599e95937ba0cc740127526.jpeg
https://exhibits.lafayette.edu/geology/files/original/bb413b726f9f845315e511c1aa8d7140.jpeg
https://exhibits.lafayette.edu/geology/files/original/5d955984d38794adcb467eea1472f34c.jpeg
https://exhibits.lafayette.edu/geology/files/original/99b3cad206ff75cd0ab2c03451d29952.JPG
https://exhibits.lafayette.edu/geology/files/original/064e2fbe166dd429abde26dfc8cb15c9.JPG
https://exhibits.lafayette.edu/geology/files/original/423a6a716ac63c1a32ebb8d89ad4a0ab.JPG
https://exhibits.lafayette.edu/geology/files/original/29e0d8b920cf5dd41ee6f2634269740f.JPG