-
Hemimorphite vs. Smithsonite
Although hemimorphite and smithsonite are different minerals with different chemical compositions and crystal structures, they have frequently been confused – especially when only simple tools were available and the specimens could not be subjected to destructive testing. Often a single specimen will be an intergrown mixture of hemimorphite and smithsonite. Until the mid-to-late 1800s, the…
-
Gemology
Hemimorphite is a favorite collector gem because it occurs in a range of spectacular colors. Some collectors seek out specimens that will cover the full range of hemimorphite’s colors. Hemimorphite should be used cautiously in jewelry. It has a Mohs hardness of only 4 ½ to 5, so it will be quickly abraded if worn in a ring or…
-
Crystal Habit
Hemimorphite exhibits a variety of crystal habits, including prismatic, tabular, and botryoidal. The crystals are often blade shaped and grow in clusters. These clusters can form a fan-like spray of blade-shaped crystals; a cockscomb similar to marcasite; or, tightly intergrown, radiating clusters that produce a botryoidal habit.
-
Physical Properties of Hemimorphite
If you attend a mineral show or visit a museum, you will see hemimorphite specimens with beautiful crystals and in spectacular colors. Most hemimorphite has an unremarkable appearance. It usually occurs in a massive or granular habit and is white, gray, colorless or brown in color. Individual crystals, when distinguishable, can be prismatic, tabular and…
-
Geologic Occurrence of Hemimorphite
Most hemimorphite is found in the rocks above and surrounding zinc deposits. Here, primary zinc ores such as sphalerite were altered to produce hemimorphite as a weathering product, or secondary mineral. Some hemimorphite is also formed where zinc-bearing rocks were subjected to metasomatism. Hemimorphite can occur as crusts that replaced primary sulfide minerals, crusts of crystals that…
-
Origin of the Name Hemimorphite
The word hemimorphic is an adjective used to describe a crystal that has terminations of different shapes at the end of its primary crystallographic axis. Adolph Kenngott knew that hemimorphite was one of just a few minerals that produced hemimorphic crystals. That inspired him to use the name hemimorphite in 1853. Prior to Kenngott’s use of the name, hemimorphite…
-
What Is Hemimorphite?
Hemimorphite is a zinc silicate mineral with a chemical composition of Zn4Si2O7(OH)2*H2O. It contains up to 54% zinc by weight and is a minor ore of zinc. Hemimorphite is a common secondary mineral found in the weathered rocks above and around zinc deposits. Most hemimorphite is white, gray, colorless, or brown. Rare specimens with nice crystals and spectacular yellow, bluish green, or…
-
Other Luminescence Properties
Fluorescence is one of several luminescence properties that a mineral might exhibit. Other luminescence properties include: PHOSPHORESCENCE In fluorescence, electrons excited by incoming photons jump up to a higher energy level and remain there for a tiny fraction of a second before falling back to the ground state and emitting fluorescent light. In phosphorescence, the…
-
Fluorescent Mineral Books
Two excellent introductory books about fluorescent minerals are: Collecting Fluorescent Minerals and The World of Fluorescent Minerals, both by Stuart Schneider. These books are written in easy-to-understand language, and each of them has a fantastic collection of color photographs showing fluorescent minerals under normal light and different wavelengths of ultraviolet light. They are great for learning about fluorescent…
-
Practical Uses of Mineral and Rock Fluorescence
Fluorescence has practical uses in mining, gemology, petrology, and mineralogy. The mineral scheelite, an ore of tungsten, typically has a bright blue fluorescence. Geologists prospecting for scheelite and other fluorescent minerals sometimes search for them at night with ultraviolet lamps. Geologists in the oil and gas industry sometimes examine drill cuttings and cores with UV…