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USE OF CRYSTAL FORMS AND HABITS IN MINERAL IDENTIFICATION

The atoms within the crystal of a mineral are arranged in a regular fashion to form a lattice, and the crystal exhibits a shape with surface regularity which reflects its internal symmetry[Ref1]. The shape of a crystal is often typical of a mineral. and often typical the location where found; thus, crystal shape comprised of crystallographic forms modulated by crystal habit can be a useful tool in mineral identification.

USES OF CLEAVAGE, PARTING, AND FRACTURE IN MINERAL IDENTIFICATION

Cleavage in a mineral is the tendency for the crystal to split along definite  crystallographic planes as exemplified by the rhombohedron cleaved from a calcite crystal shown in Figure 1[Ref1]. These planes of weakness are present within a regular repeating array of atoms and ions within the crystal and are always parallel to a potential face of the crystal.

FRACTURE IN MINERAL IDENTIFICATION

Fracture in mineralogy is the texture and shape of the surface formed when the mineral is fractured. Fracture differs from cleavage and parting, which involve clean splitting along a plane surface, as it produces rough irregular surfaces [Ref1]. The appearance of fracture surfaces among minerals is highly varied and is a useful tool in identification. In this part of my Blog I’ll describe the fracture surfaces broadly seen in minerals.

GALLERY OF CHINESE CARVED JADE ART

o the great advantage of the beauty of their art, Chinese carvers of jade were guided by themes and decorative motifs in the shaping of their carvings and the choices of decorative motifs adorning them[Ref1-7].

HISTORY OF JADE CARVING IN CHINA

From the late Neolithic Age (circa 3500 BC-2070 BC) into today the crafting of jade art objects in China has produced beautiful and magnificent art objects which exhibit remarkable diversity of both color and form as shown by the carved nephrite jade pendant with phoenix pattern and the funerary Bi Disc with rain pattern in Figure 1[Ref1]. In this blog I’ll describe the tools and techniques with their technological advances and show corresponding art objects of increasing complexities of design and execution.

MINERAL STUFF: THE GEMSTONE JADE

Since ancient times jade[Ref1] has been used by artisans to create beautiful jewelry and works of art. Art objects of jade have been carved in China for more than 6000 […]

PALEONTOLOGY OF AMBER

In this Blog I’ll describe how biomaterials including animal and plant fossils are included and preserved in amber formed from tree resin, which by its stickiness can entrap objects which […]

MINERAL STUFF: AMBER, THE GEM

Amber is a hard resin formed from tree sap by fossilization and is many millions of years old[Ref1]. Since Neolithic times (about 9000-3000 BC) and before the Copper Age[Ref]2) amber […]

Precious Coral

Both precious red and black corals are bottom-dwelling sessile marine branched animals that have been harvested at depths between 60 and 20,000 feet [Ref 1, Ref 2]. They have provided […]

Ancient Rubies

In this continuation of blogs about the corundum gem varieties, sapphire and ruby, I will first describe the trade routes that first brought the gems, from their mines in the […]