How do i determine if a rock is qtz-norm, ol-norm, hy-norm or ne-norm?

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In summary, to determine the normative mineral for your rock based on the data given, convert the weight % of each element to molecular % and allocate them to idealized mineralogies. Then compare the norm values to determine the normative mineral.
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subopolois
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i have a rock that has been chemically anaylzed, all oxides are determined. the question is asking me to determine which is qtz-normative,, olivine-norm, hypersthene-norm or nephtaline-norm. ho do i determine which one it is based on the data i am given. the question also gives norm values for many minerals
 
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First, convert the weight % of each element to molecular %. Then allocate the molecular % to idealized mineralogies in a logical progression. If there is a silica deficit, then there are more calcs necessary until the deficit is eliminated.

There are Excel spreadsheets available on the internet for this, but don't try if you're not good with chemistry. There's also more than one way (convention) to do this.
 
  • #3


Based on the data you have been given, you can determine which mineral is normative by comparing the norm values for each mineral. Look for the mineral with the highest norm value and that will be the normative mineral for your rock. For example, if the norm value for quartz is the highest, then your rock is qtz-normative. If the norm value for olivine is the highest, then your rock is olivine-normative, and so on. Make sure to double check your calculations and data to ensure accuracy.
 

What is the difference between qtz-norm, ol-norm, hy-norm, and ne-norm?

Quartz-norm refers to rocks that primarily contain the mineral quartz, while ol-norm refers to rocks that primarily contain olivine. Hy-norm refers to rocks that contain a significant amount of hydrous minerals, such as serpentine or talc. Ne-norm refers to rocks that contain a significant amount of nepheline or feldspathoids.

What are the key characteristics to look for when determining if a rock is qtz-norm, ol-norm, hy-norm, or ne-norm?

When determining the normative mineralogy of a rock, it is important to look at the mineral composition, texture, and overall color. Quartz-norm rocks will have a high percentage of quartz and may have a light color, while ol-norm rocks will have a high percentage of olivine and may have a greenish color. Hy-norm rocks will have a high percentage of hydrous minerals and may have a greasy or waxy texture. Ne-norm rocks will have a high percentage of nepheline or feldspathoids and may have a darker color.

How can I test for the presence of hydrous minerals in a rock?

The most common method for testing for the presence of hydrous minerals is through the use of a hand lens or microscope. Hydrous minerals often have a distinct greasy or waxy appearance, which can be easily observed under magnification. Additionally, chemical tests can be performed to determine the presence of specific hydrous minerals.

Can a rock contain more than one type of normative mineralogy?

Yes, it is possible for a rock to contain more than one type of normative mineralogy. For example, a rock could have both quartz and olivine as its primary minerals, making it a mix between qtz-norm and ol-norm. It is also possible for a rock to have a mixture of hydrous minerals and nepheline or feldspathoids, making it a combination of hy-norm and ne-norm.

Why is it important to determine the normative mineralogy of a rock?

Determining the normative mineralogy of a rock is important because it provides valuable information about the rock's formation and geological history. It can also help in identifying the rock and understanding its properties, such as strength and weathering potential. Additionally, the normative mineralogy can provide insights into the composition of the Earth's crust and the processes that have shaped it over time.

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