3922 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
or rare plastic deformation lines/lamellae running along
cleavage planes across dodecahedroid brown-coloured dia-
monds (Figure 3p).
Diamond Breakage Patterns
The diamond breakage patterns can be classified in two.
The first is associated with geological processes and the sec-
ond with comminution and transport processes applied to
extract the valuable stones from the host kimberlite ore.
Fracture Associated with Geological Processes
(A Crystallographic Control)
The magmatic eruptions that bring diamonds to the sur-
face are volatile charged, fast-moving, and typically violent.
As the diamonds ascend, they undergo inherent stresses
that can lead to natural breakage. Distinguishing between
natural and mechanically induced diamond breakage can
be challenging. While the general rule-of-thumb suggests
that mechanically broken stones display sharp, un-resorbed
Figure 3. A flow-chart showing typical morphologies and surface features (stippled blue lines) of the Roberts Victor diamonds.
Breakage zones are delineated by stippled yellow lines. (a) sharp-edged octahedral crystal with a typical rosette-shaped
sulphide inclusion. (b) twinned macel. (c) two-stone aggregate, with crystal distortion and Newton’s rings outlined in yellow.
(d) triangular growth plates on the {111} face. (e) imbricated growth plates on the {111} face. (f) Macel with step-face features
along the sides and significant fracturing at the corners of the stone. (g) tightly spaced step-faces forming striations on the
{111} face. (h) shield-shaped octahedra forming an aggregate. (i) shield-shaped octahedra with serrated lamellae on {111}. (j)
negative, flat-bottomed (f/b) and truncated trigons present on all faces of the highly resorbed octahedra. (k) brown octahedra
exhibiting typical trigons. (l) “pin-cushion” macel with significant surface ribbing. (m) transitional diamond with ditrigonal
faces. (n) tetrahexahedral crystal. (o) transitional stone with trigonal faces. (p) dodecahedron with surface lamellae/lines
running along cleavage
or rare plastic deformation lines/lamellae running along
cleavage planes across dodecahedroid brown-coloured dia-
monds (Figure 3p).
Diamond Breakage Patterns
The diamond breakage patterns can be classified in two.
The first is associated with geological processes and the sec-
ond with comminution and transport processes applied to
extract the valuable stones from the host kimberlite ore.
Fracture Associated with Geological Processes
(A Crystallographic Control)
The magmatic eruptions that bring diamonds to the sur-
face are volatile charged, fast-moving, and typically violent.
As the diamonds ascend, they undergo inherent stresses
that can lead to natural breakage. Distinguishing between
natural and mechanically induced diamond breakage can
be challenging. While the general rule-of-thumb suggests
that mechanically broken stones display sharp, un-resorbed
Figure 3. A flow-chart showing typical morphologies and surface features (stippled blue lines) of the Roberts Victor diamonds.
Breakage zones are delineated by stippled yellow lines. (a) sharp-edged octahedral crystal with a typical rosette-shaped
sulphide inclusion. (b) twinned macel. (c) two-stone aggregate, with crystal distortion and Newton’s rings outlined in yellow.
(d) triangular growth plates on the {111} face. (e) imbricated growth plates on the {111} face. (f) Macel with step-face features
along the sides and significant fracturing at the corners of the stone. (g) tightly spaced step-faces forming striations on the
{111} face. (h) shield-shaped octahedra forming an aggregate. (i) shield-shaped octahedra with serrated lamellae on {111}. (j)
negative, flat-bottomed (f/b) and truncated trigons present on all faces of the highly resorbed octahedra. (k) brown octahedra
exhibiting typical trigons. (l) “pin-cushion” macel with significant surface ribbing. (m) transitional diamond with ditrigonal
faces. (n) tetrahexahedral crystal. (o) transitional stone with trigonal faces. (p) dodecahedron with surface lamellae/lines
running along cleavage