$8.66
DESCRIPTION-> Click "Learn more about this item" for article & instructions!
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Freshwater and saltwater pearls are made of aragonite. "Nacre" is the name for the pearl material which consists of alternating layers of inorganic aragonite and an organic film produced and deposited by the residing animal. "Nacre, also known as mother of pearl, is an organic–inorganic composite material produced by some molluscs as an inner shell layer....It is strong, resilient, and iridescent." [from Wikipedia]. Many types of corals produce aragonite as a framework to grow upward from.
This listing is for an aragonite consisting of smooth spherical to ovoid particles from about 0.43 mm to 0.72 mm with some pieces outside that range. This type is usually referred to as "oolitic" aragonite, composed of oolites. The most common size is towards the lower end of that, about 0.50 mm. There are a few pieces which originate from thin seashells and so are in a flat form but 99.5% of it is shaped as rounded particles. It is very free flowing and "slippery" because of the particle shape, similar to the reflective glass beads we carry. On the term oolitic or oolite, Wikipedia says this: "Strictly, oolites consist of ooids of diameter 0.25–2 millimetres; rocks composed of ooids larger than 2 mm are called pisolites. The term oolith can refer to oolite or individual ooids."
Oolitic aragonite sand is from a marine source (but does not include any pearls!). On a technicality aragonite is stable at normal temperatures and pressures on earth, unlike the much more common form of CaCO3, calcite. Aragonite is a form of calcium carbonate that is the stable form of that compound at higher pressures but not necessarily at higher temperatures alone. If aragonite is taken to high temperatures without an accompanying increase in pressure, aragonite will spontaneously convert into calcite. Aragonite is denser and harder than calcite. Why does aragonite even exist in the amounts it does? In some conditions the crystallization of calcite is discouraged by factors not fully known and aragonite will crystallize instead. The magnesium and salt content of the crystallizing liquid and the stability of the fluid are involved, as are others. Over geological time aragonite will convert naturally to calcite, especially in locations where temperatures reach 400 C (750 F).
Calcium carbonate refers only to a chemical compound (CaCO3). It says nothing about the crystal structure of CaCO3 minerals. There are 3 types of CaCO3 minerals: aragonite, calcite, and vaterite. The crystalline structure of those three are different and some of their physical properties differ, such as density and hardness. Aragonite has a orthorhombic crystal form. Calcite has a trigonal form, and the rare vaterite has a hexagonal crystal form.
Usually CaCO3 is only available in a powdered form. This listing is for a roughly spherical particle sand form. Many inexpensive fillers are silica based or mixtures of silicates and other oxides. Those fillers will be much harder materials with mohs hardnesses of up to 7. Aragonite is much softer than that but is a form that is slightly harder than the marble or limestone types with a mohs hardnesses of around 3.5 to 4 (other calcium carbonates are around 3 on the mohs scale).
Aragonite comes from several sources, several of which involve the deposition in layers of CaCO3, one being biological from marine or freshwater occurrences such as in mollusks, coral, shells, and other natural water based organisms. Such organisms are able to secrete aragonite from water that would ordinarily only produce a different form of CaCO3, calcite. As mentioned above, pearls of aragonite form in marine oysters and freshwater mussels in layers as a natural defence against an irritant such as a parasite or sand grain entering their shell, preventing damage to their fragile bodies. It forms in the ocean as part of inorganic processes involving the precipitation of "marine cements" in layers similar to that found on land in caves. The deposits in caves from physical processes are called speleothems, which are found in carbonate caves. CaCO3 dissolved in water drips in the same spots over centuries and millennia to form stalactites or stalagmites found in caves as the CaCO3 comes out of solution and deposits layers of the spikey aragonite mineral in layers around the formations as they enlarge (other shapes are columns, draperies, flowstone, and straws).This sand forms in tropical waters through precipitation and sedimentation. The rounded aragonite sand in the Bahamas is the largest deposit in the world. It forms in a similar way that pearls are constructed. It aggregates around a tiny piece of calcium carbonate in shallow warm waters by dissolved CaCO3 in high energy surf coming out of solution and sticking to the tiny aragonite sand grain in layers. Another location where it forms is around the Great Salt Lake in the US.
For those with metaphysical inclinations, aragonite is said to foster truth, understanding and an unclouded perception of reality. Aragonite is supposed to increase energy, boost self-confidence and feelings of self-worth as you learn to place trust in yourself. Aragonite has a strong relationship with the natural world. This stone will always lift you ahead and start you straight and balanced. It is beneficial to those who have spent more time drifting in the ethereal realm or have lost touch with the earth under their shoes.
Although aragonite is a form of calcium carbonate and CaCO3 has many uses, aragonite is definitely not the mainstream source for CaCO3 (one niche use for aragonite specifically is in marine aquariums, as a substrate layer which helps maintain a proper pH of 8.2 without the use of chemicals). The source for most calcium carbonate is the mineral limestone (also chalk and marble), which is ground to various particle sizes and purified to varying degrees for whiteness). Widely used as a filler in many products, it is whiter and more opaque than other fillers. It has a great many other uses, from construction to pharmaceuticals. The Wikipedia article is a good one, & is here:
https://en.wikipedia.org/wiki/Calcium_carbonate
The article touches on it's use as a filler and extender for both thermoplastic and thermoset polymers:
"Calcium carbonate is a common substance found in rocks as the minerals calcite and aragonite (most notably as limestone, which contains both of those minerals) and is the main component of pearls and the shells of marine organisms, snails, and eggs. Calcium carbonate is the active ingredient in agricultural lime and is created when calcium ions in hard water react with carbonate ions to create limescale. It is medicinally used as a calcium supplement or as an antacid, but excessive consumption can be hazardous... Industrially important source rocks which are predominantly calcium carbonate include limestone, chalk, and marble....The main use of calcium carbonate is in the construction industry, either as a building material or limestone aggregate for road building or as an ingredient of cement or as the starting material for the preparation of builder's lime by burning in a kiln. However, because of weathering mainly caused by acid rain, calcium carbonate (in limestone form) is no longer used for building purposes on its own, but only as a raw/primary substance for building materials...[used] In the oil industry..as a raw material in the refining of sugar from sugar beet...as a filler in paper...as an extender in paints...a popular filler in plastics...as a white paint, known as whitewashing...in ceramics/glazing applications....as a food additive...a gastric antacid...and agricultural lime."
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Mar 15, 2023
Steve’s aragonite “sand” caught my eye because his extensive product description is copious, educating, fun to read, and most of all: 100% scientifically accurate. I did my research way in advance of finding Steve’s aragonite. There are other calcite oolite products online elsewhere but I took a stab and searched Etsy. Glad I did. Buying from small business owners is preferable to me because my family has been small business owners over several generations going back more than 120 years. I plan to buy aragonite oolites only from Steve. Next order I will post how my application went. Thanks, Steve!
James