Table of Contents
- 1 What is feldspar look like?
- 2 What is the texture of feldspar?
- 3 What is the physical properties of feldspar?
- 4 What is feldspars crystal structure?
- 5 What makes up the structure of a feldspar crystal?
- 6 Which is the best description of a feldspar?
- 7 What is the angle between the faces of the feldspars?
What is feldspar look like?
Feldspars usually are white or nearly white, though they may be clear or light shades of orange or buff. They usually have a glassy luster. Feldspar is called a rock-forming mineral, very common, and usually makes up a large part of the rock. Other differences: quartz is usually clear and feldspar is usually cloudy.
What is the texture of feldspar?
The perthitic texture may be coarse and easily visible as slight variations in color in the crystal, or it may be microscopic and practically invisible. The coarseness of the texture depends mostly on the rate at which the feldspar was cooled the slower the cooling, the coarser the texture.
What type of crystal system is feldspar?
Monoclinic – triclinic
| Feldspar | |
|---|---|
| Crystal system | Monoclinic – triclinic |
| Habit | Prismatic, often twinned |
| Cleavage | Good to perfect |
| Fracture | Conchoidal |
What is the physical properties of feldspar?
| Generalized Physical Properties of Feldspar Minerals | |
|---|---|
| Chemical Classification | Silicate |
| Mohs Hardness | 6 to 6.5 |
| Specific Gravity | 2.5 to 2.8 |
| Diagnostic Properties | Perfect cleavage, with cleavage faces usually intersecting at or close to 90 degrees. Consistent hardness, specific gravity and pearly luster on cleavage faces. |
What is feldspars crystal structure?
Sanidine and orthoclase are monoclinic or nearly so; the plagioclase feldspars are triclinic. Ordering in feldspars is based on the distributional pattern of silicon and aluminum within the different tetrahedrons. …
How do feldspars form?
Feldspar is the name of a group of rock-forming minerals which make up as much as 60% of the Earth’s crust. Feldspars crystallize from magma in both intrusive and extrusive rocks, and they can also occur as compact minerals, as veins, and are also present in many types of metamorphic rock.
What makes up the structure of a feldspar crystal?
The structure of a feldspar crystal is based on aluminosilicate tetrahedra. Each tetrahedron consists of an aluminium or silicon ion surrounded by four oxygen ions. Each oxygen ion, in turn, is shared by a neighbouring tetrahedron to form a three-dimensional network.
Which is the best description of a feldspar?
Feldspars usually are white or nearly white, though they may be clear or light shades of orange or buff. They usually have a glassy luster. Feldspar is what’s called a rock-forming mineral, very common and usually making up a large part of the rock.
How are the silica groups of feldspars formed?
Feldspars lie along one of two solid-solution series, the plagioclase feldspars and the alkali or potassium feldspars. All of them are based on the silica group, consisting of silicon atoms surrounded by four oxygens. In the feldspars the silica groups form rigid three-dimensional interlocking frameworks.
What is the angle between the faces of the feldspars?
The angle between the face that intersects the b axis and is parallel to a and c and the face that intersects the c axis and is parallel to a and b is 90° for the monoclinic feldspars and ranges from about 86° to roughly 89°30′ for the triclinic feldspars; the deviations from 90° are not readily discernible with the naked eye.