What are the optical properties of feldspar?
What are the optical properties of feldspar?
Mineral Group: Feldspar group, plagioclase series….Anorthite Optical Properties.
| Color / Pleochroism | White, grayish, reddish; colorless in thin section |
|---|---|
| 2V: | Measured: 78° to 83°, Calculated: 78° |
| RI values: | nα = 1.573 – 1.577 nβ = 1.580 – 1.585 nγ = 1.585 – 1.590 |
| Optic Sign | Biaxial (-) |
| Birefringence | δ = 0.012 – 0.013 |
What are the properties of potassium feldspar?
POTASSIUM FELDSPAR
- Chemical Composition: KAlSi3O8.
- Hardness: 6.
- Color: Flesh-colored, pink, white, green or gray.
- Specific Gravity: 2.6.
- Cleavage Planes: Two perfect, at right angles.
- Crystal Structure: Prism-shaped crystals.
- Luster: Nonmetallic.
- Other Properties: Common mineral (orthoclase is a common variety).
How do you identify K feldspar?
In general, keys to identifying K-feldspar are its (lack of) color, its low birefringence, and its twinning. In thin section, microcline, orthoclase and sanidine are distinguished by their twinning, optical sign, and 2Vo.
What is potassium feldspar used for in everyday life?
Feldspars play an important role as fluxing agents in ceramics and glass production, and are also used as functional fillers in the paint, plastic, rubber and adhesive industries.
Where are the clear grains on the K-feldspar?
The clear grains with low birefringence left of the K-feldspar are quartz , and minor plagioclase (feldspar) is in the extreme lower left. The feldspars and quartz are difficult to distinguish in the PP view, although the feldspars are a bit cloudier due to incipient alteration.
What are the optical properties of a food?
In the case of foods, the main optical property considered by consumers in evaluating quality is color, followed by gloss and translucency, or turbidity, and other properties of much lower interest. Light can be defined as the visible part of the whole electromagnetic spectrum (wavelengths between 380 and 770 nm).
What are the exsolved lamellae of K-feldspar?
The K-feldspar grain above it, on the edge of the photo, contains fine exsolved lamellae of albite (visible as stripes in XP). Minor plagioclase is also present, and also a few small patches of green biotite.
What does a K feldspar crystal look like?
K-feldspar crystals are typically tabular and often elongate. Exsolved Na- plagioclase may give them a wormy or ribbony appearance (perthite). Although there are two good cleavages, they may not be well displayed. · Color – colorless, but may be altered giving it a grainy or grayish appearance.