<p>I would say that cations would control the structure in several ways; in the case of aluminum octahedra in aluminosilicates, for example, they might completely influence it by causing the presence of completely separate alternating layers of bonded octahedra. The octahedra may even dominate the unit-cell, appearing in a larger numerical and volumetric capacity than the tetrahedra.</p>

<p>Additionally, the different bonded cations have different polarities, and by extension, exert different forces on the relevant bonds; this plays a <strong>huge</strong> role in determining how the structure responds under conditions of high pressure relevant to the Earth's interior, e.g determining where shearing takes place, etc.</p>

CC BY-SA 3.0
2015-11-15T19:57:48.817Z
2015-11-15T19:57:48.817Z
Anant Hariharan
<p>Beyond the obvious fact that in many of the silicate subtypes they play an ionic 'glue' like role by bonding the tetrahedra units together; how do cations <strong>control</strong> the structure of a silicate and how does it vary between different cations and silicates?</p>

CC BY-SA 3.0
2015-11-17T05:07:19.140Z
An answer to this question would be a book with chapters about mineralogy, chemistry, physics and crystallography. I think it's better to edit and focus the question a bit more, also to clarify it a bit.
Gimelist
<geology><mineralogy><crystallography>
How do cations control the crystal structure of silicate minerals?
Lewis
# How do cations control the crystal structure of silicate minerals?

(Asked by: username_0 on 2015-11-15)

Beyond the obvious fact that in many of the silicate subtypes they play an ionic 'glue' like role by bonding the tetrahedra units together; how do cations **control** the structure of a silicate and how does it vary between different cations and silicates?

**Tags:** geology, mineralogy, crystallography

> **Comments:**
> **username_1**: An answer to this question would be a book with chapters about mineralogy, chemistry, physics and crystallography. I think it's better to edit and focus the question a bit more, also to clarify it a bit.  

---

## 1 answers

### Answer by username_2 on 2015-11-15. Score: 2

I would say that cations would control the structure in several ways; in the case of aluminum octahedra in aluminosilicates, for example, they might completely influence it by causing the presence of completely separate alternating layers of bonded octahedra. The octahedra may even dominate the unit-cell, appearing in a larger numerical and volumetric capacity than the tetrahedra.

Additionally, the different bonded cations have different polarities, and by extension, exert different forces on the relevant bonds; this plays a **huge** role in determining how the structure responds under conditions of high pressure relevant to the Earth's interior, e.g determining where shearing takes place, etc.


---

