Biomineralisation Intro

Question 1

What is mineral dissolution in terms of bonds?

Answer 1

Breaking bonds

Question 2

Whats is mineral formation in terms of bonds?

Answer 2

Forming bonds

Question 3

What are the three processes of nucleation?

Answer 3

1. Nucleation
2. Growth of initial phase
3. Growth of crystalline phase

Question 4

What does nucleation involve?

Answer 4

The formation of a nucleus (new phase mineral) within an old phase solution.
Generally SI > 0 (supersaturated solution in terms of the required ions).

Nucleation tends to occur by random collision of ions on a surface, where the surface acts as a catalyst to reduce activation energy.

Question 5

What happens during the initial growth phase?

Answer 5

Ions adsorb initially at the nucleus.

Initially Amorphous - Hydrated, soluble, no crystal lattice.
Nucleation faster in amorphous phase than crystalline phase.

Then become crystalline.

Question 6

What happens during the growth of crystalline phase?

Answer 6

Crystalline phases uses the amorphous phases as a template.

Like when ice cream goes gritty.

Question 7

What does the saturation index tell you?

Answer 7

If a mineral can precipitate or dissolve under the environmental conditions.

Question 8

What is the relationship between the Ion activity product (Q) and solubility product (Ksp)?

Answer 8

Q = Ksp : Equilibrium

Q < Ksp : SI < 0 : Undersaturated (can dissolve)

Q > Ksp : Si > 0 : Supersaturated (precipitates)