At the Field Museum in Chicago with @aaronflav
Drool.
I have an intense love of quartz.
The Cave of Crystals near Chihuahua, Mexico.
Those giant crystals of gypsum (CaSO4) probably grew to their massive size really slowly in a bath of hot water and dissolved minerals. Now that the water has been pumped out by industrial miners, scientists are free to explore…with the help of some ice-cooled orange jumpsuits: The caves average a termperature of 118 F, and 90 % humidity.
Ulexite, NaCaB5O6(OH)6 · 5 H2O.
Ulexite grows in clusters of aligned fibers. Perpendicular to the fibers, the material is able to transmit light due to total internal reflection (upper photo). If you turn the stone on its side, it is completely opaque (lower photo).
(Source: etsy.com)
H2O.
Fact: There are (at least) 15 crystal structures of ice, which are favored at different temperatures and pressures.
(Source: its.caltech.edu)
Amethyst.
Great for activating creative energies and promoting vivid dreams.
Also, I need these necklaces, wow.
Stibnite, Sb2S3.
Stibnite gets its name from the old word for the element antimony, stibium. This is also where antimony’s curious Sb symbol comes from. For this confusion, we have Jöns Jacob Berzelius to thank.
Bixbyite, (Mn,Fe)2O3, is a mixed manganese/iron oxide.
A crystal structure is a repeating pattern of where atoms go. Each site is usually occupied by a specific element, but sometimes one element can stand in for another if they are chemically similar. For example, in Bixbyite, while oxygen sites are only occupied by oxygen, metal sites are randomly occupied by either manganese or iron.
In short: Bixbyite doesn’t discriminate.
(Source: johnbetts-fineminerals.com)
Euclase sample from Lost Hope Mine in Zimbabwe.
Euclase is a beryllium aluminum hydroxide silicate, BeAlSiO4(OH), but this intense blue comes from charge transfer bands in the iron impurities. When electrons move from an iron +2 ion to an iron +3 ion, the emitted light is this beautiful blue color.
(Source: irocks.com)
Graphite (left) and diamond (right).
Each is made of only carbon, but one is soft enough to smear on paper, and the other is referred to as the hardest substance on earth. How do we get such different properties from the same element? The answer is in their crystal structures.
Graphite is made of strong sheets of carbon, but the chemical bonds between the sheets are very weak. When you make a pencil line on paper, the graphite’s sheets stay intact, but they are pulled apart from one another. Diamond is a 3-dimensional network of strong bonds, making the crystal too strong for you to slide apart on a piece of paper.
