What is plagioclase feldspar rich in?
The Plagioclase series is a group of related feldspar minerals that essentially have the same formula but vary in their percentage of sodium and calcium.
Is plagioclase feldspar calcium rich?
The plagioclase feldspar family is the most common mineral family in the earth’s crust. It is almost ubiquitous in igneous rocks. Gabbros, basalts and anorthosites tend to have more calcium-rich plagioclase, generally labradorite.
What are the varieties of plagioclase feldspar?
Plagioclase series members
| Name | % CaAl2Si2O8 | % NaAlSi3O8 |
|---|---|---|
| Bytownite | 70–90 | 30–10 |
| Labradorite | 50–70 | 50–30 |
| Andesine | 30–50 | 70–50 |
| Oligoclase | 10–30 | 90–70 |
How do I know if I have plagioclase feldspar?
It is usually easy to distinguish plagioclase feldspars because their two planes of cleavage intersect at 90-degree angles, and their cleavage faces often display striations. These properties make plagioclase feldspars relatively easy to identify with a hand lens in coarse-grained igneous and metamorphic rocks.
What is feldspar used for?
Feldspars are used widely in the glass and ceramics industries. Alkali feldspars are more commonly used commercially than plagioclase feldspars. Albite, or soda spar as it is known commercially, is used in ceramics.
What is difference between feldspar and orthoclase?
Plagioclase feldspars lack potassium, are light colored and are usually striated. Orthoclase is the more common of the k-spars. The differences between these minerals are minor in hand samples. Microcline tends to be deeper-colored and is the only one that can be, but is not always, a blue-green color (amazonite).
How are the plagioclases different from the feldspars?
Generally, feldspars can be divided into three main groups: Plagioclase feldspars (Na or Ca): NaAlSi 3 O 8 – CaAl 2 Si 2 O 8 (albite and anorthite) Alcalic feldspars (K or Na): K/NaAlSi 3 O 8 (albite and all K-feldspars)
What kind of rocks are in the plagioclase series?
Mineral Group: Feldspar group, plagioclase series. Environment: Igneous and metamorphic rocks. Group name for Na, Ca feldspars.
Who was the first person to discover plagioclase?
Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more properly known as the plagioclase feldspar series. This was first shown by the German mineralogist Johann Friedrich Christian Hessel (1796–1872) in 1826.
How are the intermediate members of plagioclase similar?
The intermediate members of the plagioclase group are very similar to each other and normally cannot be distinguished except by their optical properties. The specific gravity in each member (albite 2.62) increases 0.02 per 10% increase in anorthite (2.75).