mineralogy tourmaline outline.docx - Outline for Paper...

Outline for Paper
Tourmaline Rock
I. Introduction
A. Tourmaline when heated or rubbed is said to create a charge that
can attract hair and dust and was used to clean chimneys in the
olden days. This gem is said to have at least 11 different colors.
II. Fundamental physical and optical properties.
A.
This gem stone can be distinguished by its three-sided prism and as
well as its vertical striations
.
III. Lattice
a. Chemical composition (range)
A(D
3
)G
6
(T
6
O
18
)(BO
3
)
3
X
3
Z
A = Ca, Na, K, or is vacant (large cations);
D = Al, Fe 2+ , Fe 3+ , Li, Mg 2+ , Mn 2+ (intermediate to small cations - in
valence balancing combinations when the A site is vacant);
G = Al, Cr
3+
, Fe
3+
, V
3+
(small cations);
T = Si (and sometimes minor Al, B
3+
);
X = O and/or OH;
Z = F, O and/or OH.

b. Coord polyhedral and structure (figure: cif model)
c. X-ray diffraction pattern (figure)
Radiation - Copper Kα
Data Set: Cruziero Mine, San Jose, Minas Gerais, Brazil 927
Data courtesy of RRUFF project at University of Arizona, used with permission.