What silicate structure does amphibole have?
Table of Contents
What silicate structure does amphibole have?
silica tetrahedra
In amphibole structures, the silica tetrahedra are linked in a double chain that has an oxygen-to-silicon ratio lower than that of pyroxene, and hence still fewer cations are necessary to balance the charge. Amphibole is even more permissive than pyroxene and its compositions can be very complex.
What kind of a silicate mineral is hornblende an amphibole )?
inosilicate
Hornblende is an inosilicate (chain silicate) mineral, built around double chains of silica tetrahedra.
What is the structure type of amphibole?
Structure. The amphibole structure consists of doubled (Si4O11)6- chains running parallel to c-axis (Fig. 4). These chains are bonded to octahedral strips consisting of three regular octahedral sites (M1, M2, M3) and one larger 6- to 8-fold site (M4).
Is hornblende a silicate or non silicate?
A single chain silicate mineral. A double-chain ferromagnesian silicate mineral (e.g., hornblende). A sheet silicate mineral (e.g., biotite).
What is a silicate structure?
silicate structural linkages. The basic structural unit of all silicate minerals is the silicon tetrahedron in which one silicon atom is surrounded by and bonded to (i.e., coordinated with) four oxygen atoms, each at the corner of a regular tetrahedron.
Is amphibole a chain silicate?
Like pyroxenes, amphiboles are classified as inosilicate (chain silicate) minerals. However, the pyroxene structure is built around single chains of silica tetrahedra while amphiboles are built around double chains of silica tetrahedra.
What is the structure of hornblende?
hornblende, calcium-rich amphibole mineral that is monoclinic in crystal structure. Hornblende’s generalized chemical formula is (Ca,Na)2(Mg,Fe,Al)5(Al,Si)8O22 (OH)2.
What is the shape of hornblende?
Petrographic Data File
| Hornblende | |
|---|---|
| Property | Value |
| Max Birefringence | 2nd to 4th order with highest interference colors in thin section in upper first or lower second order. |
| Elongation | Prismatic crystal that can be, but is not necessarily, elongated. Crystals are often hexagonal. |
| Extinction | Symmetrical to cleavages |
How do you identify hornblende?
Identification of Hornblende Hornblende minerals as a group are relatively easy to identify. The diagnostic properties are their dark color (usually black) and two directions of excellent cleavage that intersect at 124 and 56 degrees.
What silicate structure does hornblende have?
Hornblende is a member of the amphibole group of more complex silicates, in which the tetrahedra are linked to form a continuous chain twice the width of the pyroxene chains. For this reason they are often referred to as double chain silicates.
What is the cleavage of hornblende?
Hornblende is black and, like all amphibole minerals, is characterized by two perfect cleavages that intersect at about 60° or 120°.
What kind of silicate is hornblende?
amphibole
Hornblende is a member of the amphibole group of more complex silicates, in which the tetrahedra are linked to form a continuous chain twice the width of the pyroxene chains. For this reason they are often referred to as double chain silicates.
What is amphibole?
Amphibole (/ˈæmfəboʊl/) is a group of inosilicate minerals, forming prism or needlelike crystals, composed of double chain SiO. 4. tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures.
What type of cleavage does hornblende have?
two perfect cleavages
Hornblende is black and, like all amphibole minerals, is characterized by two perfect cleavages that intersect at about 60° or 120°.
Are amphibole and hornblende the same?
Hornblende is a field and classroom name used for a group of dark-colored amphibole minerals found in many types of igneous and metamorphic rocks. These minerals vary in chemical composition but are all double-chain inosilicates with very similar physical properties.
What type of cleavage does amphibole have?
The combination of prismatic form and two diamond-shaped directions of cleavage at about 56° and 124° is the diagnostic feature of most members of the amphibole group.
