Apatite is a phosphate mineral and can come in a wide variety of colors. There are three different subtypes of apatite: fluorapatite, chlorapatite, and hydroxyapatite. Apatite can form in a wide variety of rocks; however, its deposits are typically found in sedimentary rocks. Furthermore, they are commonly found in marine and lake environments. Interestingly, they can form from organic remains like teeth, scales, and bones. They can also be precipitated during chemical weathering or deposited by groundwater. Apatite has a lower hardness, around five on the Mohs hardness scale, so it is often too brittle to be cut into gemstones. However, apatite that has formed from hydrothermal fluids is cut into gemstones and valued highly for their intense colors. These gemstones are usually not placed in a jewelry setting because they are too fragile; instead, they are merely collected for their beauty. Alongside its beauty, apatite is valued for its phosphate content and is one of the primary ores for it. Phosphate is a crucial component for fertilizer. Without the surplus of apatite in phosphate rock, the world would not be able to meet the demand for fertilizer (King¹). Whether you collect apatite or bury it, you’ll always have an appetite for more!

Aragonite is a carbonate mineral and a polymorph of calcite. For context, a polymorph is when different minerals have the same chemical composition, but the atoms are arranged differently. The arrangement of atoms impacts the appearance of the mineral. For example, aragonite usually has protruding, hexagonally shaped crystals while calcite’s crystals are rhombus shaped. Aragonite is found in a variety of inorganic environments where element-rich fluids are present like hot springs, hydrothermal ore veins, evaporite deposits, and more. When aragonite is precipitated out of the fluid, it can be found crystallized in sedimentary, igneous, and metamorphic rocks. Interestingly, aragonite can also be a byproduct of organic activity and is found in coral and pearls. Aragonite has some unique features. To start with, it is a carbonate mineral, so it reacts with hydrochloric acid. Some specimens of aragonite can also show fluorescence under ultraviolet light. However, due to its reactive nature and overall low hardness, aragonite does not have many practical applications (“The Mineral Aragonite”⁶). With that being said, its unique crystal shapes never fail to impress those I show it to, making it valuable to me.

Although lapis lazuli cannot enchant things in real life, it is still a fascinating material. To preface, lapis lazuli is not a mineral, it is a metamorphic rock. However, this rock can be sculpted to form gemstone shapes. The rich blue color comes from the silicate mineral lazurite. To be considered lapis lazuli, the rock must contain at least 25% lazurite. The gold flakes or veins sometimes seen in lapis lazuli are not actually gold, but rather pyrite. Lapis lazuli forms near where marble and/or limestone have been altered by either hydrothermal fluids or contact metamorphism. These areas are usually associated with igneous rock intrusions. Although lapis lazuli is usually sourced from Afghanistan, trace amounts have been found in Colorado. Lapis lazuli is prized for physical appearance over its applications. It is usually used as a pigment in paint or in jewelry. Lapis lazuli is relatively soft, around a five on the Mohs hardness scale, so it cannot be used for much else (King²). That being said, it is an enchanting rock to admire!

The gemstone Ruby is technically a variety of the oxide mineral corundum, rather than a distinct mineral. This type of corundum is differentiated from other forms because of its characteristic red hues. The distinctive red is produced by trace amounts of chromium. To illustrate the idea of mineral impurities, another variant of corundum with the same chemical formula as ruby is sapphire. High quality, gem-grade Corundum are usually found in metamorphic rocks, like gneiss, or in igneous rocks, like basalt. Corundum is a very hard mineral with a Mohs hardness of 9. This means that the mineral itself, not its host rock, is resistant to weathering. This makes it easy to find corundum in streams after their host rocks have been weathered away. Corundum can be mined but it is difficult and costly due to the small size in which it is found. However, corundum hardness and clarity make it valuable for jewelry. It should be noted that ruby is commonly heated to make the color more intense and to remove other impurities from it before it is placed in a jewelry setting (King³). Additionally, corundum's hardness allows it to be used as an abrasive. Working with corundum may be tough, but it sure is a beautiful site to see!

Siderite is a carbonate mineral with a high amount of iron in it. This mineral is typically found in two environments: deposited in metamorphic iron formations from a hydrothermal fluid or precipitated in iron rich sedimentary rocks. Moreover, siderite was found and mined at the Eagle Mine in Colorado. Interestingly, when siderite is found in sedimentary rocks, it can sometimes preserve casts of plant fossils. Even though it is a carbonate mineral, it is not as reactive as other carbonates and only reacts with hot hydrochloric acid. On the Mohs hardness scale, siderite ranks relatively low and measures to about a 4. This means that siderite is often too weak to be carved into gemstones or used in jewelry. However, it is considered an iron ore due to its high iron concentration. It should be noted that magnetite and hematite produce the majority of our iron ore as it is more profitable. Also, siderite, especially when it is chemically weathered to limonite, can be used as a pigment (Ridgley⁵). Just be careful, I heard siderite is a fair weathered friend!

Black tourmaline, also known as schorl, is a semi-precious gemstone. Tourmaline is highly sought after because it comes in a variety of colors, has a unique response to light, and is capable of generating electricity. To start, tourmaline forms in igneous or metamorphic rocks because it needs high temperature and pressure conditions. Tourmaline crystallizes during metamorphism, following igneous processes, as hydrothermal fluids collect and deposit the necessary elements for its formation. The characteristics of tourmaline are dependent on the availability of elements like boron, the chemical composition of the surrounding rocks, the temperature and pressure conditions, and the lifespan of the hydrothermal fluids. One unique characteristic found in some tourmaline specimens is an optical property called pleochroism. This means that some samples can show different colors at different angles of the gemstone in light. Another interesting characteristic of tourmaline is its electrical properties. Tourmaline can generate electricity when subjected to a substantial amount of pressure or heat. The electrical properties of tourmaline have allowed it to be used alongside sensitive instruments like spectrometers and sonar equipment. Schorl is specifically used as black pigment in ceramic glazes and as an abrasive material for polishing (Mahmut⁴). Now you can see why schorl is the dark horse of my collection.