What is a gemstone?
A gemstone is a valuable or semi-valuable stone that typically is cut and polished for use in a piece of jewelry.
How are gemstones formed?
Gemstones formed in nature require special ingredients, high temperatures, high pressures, time, and space to form. Some are created deep within Earth and are associated with igneous rock. Others associated with metamorphic rock are changed from other materials due to very high temperatures and pressures. Some gemstones form due to water depositing sediments and large pressures pressing the materials together such as those associated with sedimentary rock. Also, some gemstones are formed when bodies of mineral-rich water cools.
What is the rock cycle?
The rock cycle is a set group of processes that form and transform the types of rock in the crust of Earth. The rock cycle transforms rock into one of the three main types: igneous, metamorphic, and sedimentary rock.
What is hardness?
Hardness is property that measures the ability of material to resist scratching.
What is the Mohs Hardness scale?
The Mohs Hardness scale is a relative scale that relates the hardness of a substance to numerical values with 10 being the hardest and 1 being the least hard material.
What is specific gravity?
Specific gravity is a property of a substance that compares the density of the substance to the density of another substance, usually water.
What is a jeweler’s loupe?
A jeweler’s loupe is a magnifying lens used to closely observe gemstones. These devices typically produce a magnification of about 10 times the normal view. The loupe is used to detect small cracks, flaws, and sometimes if the gemstone is natural or synthetic.
What is luster?
Luster is a property of a substance that describes the substance’s ability to reflect light.
What are different ways luster is described?
Adamantine – a non-metallic, transparent mineral that has a very bright shine
Greasy – a nontransparent mineral that appears to have a thin coating or oil or grease on the surface
Waxy – a mineral that has a dull appearance and looks to have the surface coated with wax
Vitreous – mineral that has a glassy appearance
Resinous – a slightly reflective mineral that has an appearance like honey, but not necessarily having the same color as honey.
Pearly – a non- to semi-reflective mineral that has an appearance like a common button found on a shirt
What is a crystal system?
A crystal system describes the regular and repeating three-dimensional arrangement of atoms in space that make up a mineral.
What are the different crystal systems?
Amorphous – a crystal with no characteristic shape that can be used for identification
Isometric – a system with four 3-fold axes of symmetry, each of which proceeds diagonally from corner to corner through the center of the cubic unit cell. The cube, octahedron, and dodecahedron are types of isometric crystals.
Hexagonal – a system with four crystallographic axes consisting of three equal horizontal, or equilateral axes at 120 degrees to each other, as well as one vertical axis which is perpendicular to the other three. This vertical axis can be longer or shorter than the horizontal axes.
Monoclinic – a system with all the axes having different lengths. Two of them, the A and the C axes, meet at 90 degrees but the third one does not.
Triclinic – a system with a three-dimensional shape like a cube, but it has been skewed or inclined to one side, making it oblique. All crystal faces are parallel to each other.
Trigonal – a type of hexagonal system with five point groups that have a single three-fold rotation axis.
Orthorhombic – a system with three axes, all of which meet at 90 degrees to each other. However, all the axes are a different length.
Tetragonal – a system with three axes that all meet at 90 degrees. The C axis is longer than the A and B axis which are the same length. A rectangular prism is an example of this system.
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What is refraction?
Refraction is the bending of light waves as they move from one medium into a different medium.
What is Refractive Index?
The refractive index provides an optical property of a substance’s ability to bend light. The larger the refractive index value, the greater the substance’s ability to bend light.
What is Snell’s Law?
Snell’s Law is used to determine the angle of incidence or refraction of a light ray as it moves from one medium into a different medium. The angles are dependent on the ratio of the velocities of the light rays in the two media.
What is double refraction?
Double refraction in a gemstone occurs when a light ray moves through a stone, is slowed, bent, and then split into two separate light rays each at different angle from the normal. The cause of some gemstones possessing this characteristic is due to an anisotropic crystal system based on the atomic structure of the crystal. Birefringence is a measure of a gemstone’s double refractivity.
What is X-Ray Fluorescence Spectrometry?
X-ray fluorescence spectrometry is a non-destructive method of determining the elements present with a material. The method uses X-rays to transition electrons within an atom from higher levels to lower energy levels. The X-rays are used to remove the inner shell electrons by ejecting them from the inner levels. The transition from energy level 2 (L shell) to energy level 1 (K shell) is called the Kα (K alpha) transition. The transition from energy level 3 (M shell) to energy level 1 (K shell) is the Kβ (K beta) transition. Each transition produces a fluorescent photon with a specific energy and wavelength that can uniquely identify the element present.
Some stones have little value, while others are prized for their appearance. What characteristics of stones are associated with gemstones? Dig into this investigation to identify common gemstones.)
