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The 8 Classes of Minerals Part 2: Carbonates, Sulfates, and Phosphates
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The 8 Classes of Minerals Part 2: Carbonates, Sulfates, and Phosphates

Introduction to Mineral Classes

In this section, the speaker introduces the remaining four classes of minerals and explains that they are all oxyanions.

Carbonates

  • Carbonates are minerals that contain the carbonate anion, CO32-, and are commonly found in biogenic sedimentary rocks and evaporite deposits.
  • Calcite is the most common carbonate mineral and is soluble in acidic solutions like rainwater. Limestone is composed primarily of calcite.
  • Limestone caves typically have large deposits of calcite crystals located throughout known as speleothems, which include stalactites, stalagmites, and flowstone.

Sulfates

  • Sulfates contain the sulfate anion, SO42-, and gypsum or hydrated calcium sulfate is a common sulfate mineral used for building and construction since ancient times.
  • Gypsum can be dehydrated into anhydrite or calcium sulfate when heated, and both minerals are often closely associated with each other. Like calcite, gypsum and anhydrite can be precipitated from evaporating seawater and dissolved out of bedrock to form large caves.

Phosphates

  • Phosphates contain the phosphate anion PO43-. A commonly encountered group of phosphate minerals is the apatite group which has the chemical formula Ca5(PO4)3(X)2 where a combination or pure fraction of chlorine, fluorine, and/or hydroxyls can fill the X-site.
  • Apatite can be an accessory mineral in igneous rocks or a component of certain sedimentary rocks that are rich in skeletal fragments like fish bones.

Mineraloids

  • Mineraloids are not really minerals since they are not crystalline. Some examples include opal, which is amorphous hydrated silica, and obsidian or volcanic glass.

Formation of Opal and Chert

In this section, the speaker explains how siliceous ooze transforms into opal over time and how opal converts to microcrystalline quartz, forming the sedimentary rock, chert.

Opal Formation

  • Siliceous ooze transforms into opal with time.

Chert Formation

  • Over even more time, opal converts to microcrystalline quartz.
  • Microcrystalline quartz forms the sedimentary rock, chert.

Silicates

In this section, the speaker introduces silicates as a class of minerals that will be covered separately due to its abundance and importance.

Introduction to Silicates

  • Silicates are a class of minerals that will be covered separately due to their abundance and importance.
Video description

With four classes down we have four to go! Here we will focus on three of those four, carbonates, sulfates, and phosphates. These are the ones with polyatomic anions, which are oxyanions. We will also discuss mineraloids, which seem like minerals but aren't. Ever want to know what makes up limestone caves? Check this out! Script by Jared Matteucci and Bryne Hadnott Watch the whole Geology playlist: http://bit.ly/ProfDaveGeo Mathematics Tutorials: http://bit.ly/ProfDaveMath Classical Physics Tutorials: http://bit.ly/ProfDavePhysics1 General Chemistry Tutorials: http://bit.ly/ProfDaveGenChem Biology Tutorials: http://bit.ly/ProfDaveBio Microbiology Tutorials: http://bit.ly/ProfDaveMicrobio Botany Tutorials: http://bit.ly/ProfDaveBotany Zoology Tutorials: http://bit.ly/ProfDaveZoo EMAIL► ProfessorDaveExplains@gmail.com PATREON► http://patreon.com/ProfessorDaveExplains Check out "Is This Wi-Fi Organic?", my book on disarming pseudoscience! Amazon: https://amzn.to/2HtNpVH Bookshop: https://bit.ly/39cKADM Barnes and Noble: https://bit.ly/3pUjmrn Book Depository: http://bit.ly/3aOVDlT