Learn the ABCs with the Mary Johnson Collection
Ever a stickler for details, Mary Johnson's Mineral Collection is full of eclectic surprises. Here is an alphabet list of some of those unique discoveries.
The Mary Johnson Collection by Aurelio AcevedoMineralogical and Geological Museum, Harvard University
Mary Johnson's collection consists of roughly 5000 specimens
From A to Z, here are 26 of the most odd, eye-catching or otherwise interesting specimens of the Mary Johnson Collection.
A: Andesite Ash
This volcanic ash was formed during the eruption of Mt St Helens in 1980. The fine grained sediment is 90% glass and was collected only a few months after the eruption in a town a few hours away from the mountain.
B: Barite
Barite usually forms crystals but when it forms in arid sandy conditions, sand grains become entrapped within. This leads to flattened, opaque layers that resemble the petals of a rose.
C: Cuprosklodowskite
These colorful rocks were placed inside a candy tin for safekeeping, and for a very good reason. Cuprosklodowskite contains uranium and is radioactive.
D: Dacite
This rock was collected by using a core drill to extract a sample of the bedrock. Dacite is an igneous rock similar to granite or andesite.
E: Elbaite
Elbaite is a type of tourmaline that can occur in many colors. This specimen is an example of a ‘watermelon tourmaline’, it starts out pink before fading into green.
F: Fluorite
Fluorite is formed of fluorine and calcium. This ‘shark tooth’ or ‘rocket’ looking crystal is pale purple but fluorite can be almost any color of the rainbow.
G: Grossular
Grossular is a kind of garnet, originally called cinnamon stone. While the label claims this rock originates from Lake Jaco, it is actually from the nearby Sierra de Cruces, and was purposefully mislabeled to protect the source of the unusual pink garnets found there.
H: Halite
Halite is salt, NaCl, the same salt found in your kitchen. While plenty of rock salt can be found buried in the earth, this unusual crystal was found in a soy sauce bottle!
I: Iridosmine
This capsule contains a very small mineral. Iridosmine is a rare alloy of very dense metallic elements osmium and iridium.
J: Jadeite
Jadeite is one of two minerals, along with nephrite, which are referred to as jade. Jade is highly valued as an ornamental stone and gem in China and Korea.
K: Kyanite
Kyanite is named for its signature blue color. This tabular crystal broke off from the edge of the larger rock it was embedded in.
L: Lava
This rock may look just like human hair but these filaments are formed from lava flows. Pele’s Hair is named for Pele, the Hawaiian goddess of fire and the volcano Kīlauea.
M: Magnetite
Magnetite, also called lodestone, is a strongly magnetic iron ore. The ‘spikes’ radiating off it are formed from smaller bits of iron aligning themselves along the magnetic field this rock emits.
N: Nitratine
Nitratine or soda niter is the sodium containing version of niter, which contains phosphorus instead. Niter is also known as saltpeter, an essential component of gunpowder.
O: Okenite
This small fuzzy creature is actually a mineral in disguise. Okerite is a silicate crystal that is just as soft as it looks.
P: Pyrite
This fool’s gold isn’t looking very golden. In its uncrystallized form, pyrite not only lacks its shiny metallic form but slowly decomposes and produces the sulfuric acid that is eating holes in its labels.
Q: Quartz
Both the white crystals and the tan base are quartz. Quartz is one of the most common crystals on Earth. It can be found in a wide array of forms, shapes and colors, from amethyst to flint.
R: Rhodochrosite
This bright pink crystal is rhodochrosite. While rhodochrosite commonly forms in hydrothermal vents, such as this specimen, some can be formed by fungi.
S: Sandstone
Sandstone, as the name implies, is a sedimentary rock formed out of compressed sand grains. The type of sandstone seen here is very flexible and resembles bread.
T: Talc
This frog (artist once known) from Kenya is carved from talc. Talc is the softest mineral and often used for carvings such as this one.
U: Ulexite
This form of ulexite is commonly called ‘television stone’. It has a natural optical effect where it will transmit a printed image from one end of the rock to the other, similar to a TV screen, giving it its name.
V: Vivianite
This vivianite formed from fossilized whale bones. The dark, nearly black color of the specimen is the result of prolonged exposure to light causing oxidation.
W: Wulfenite
Despite this mineral's color, it's not gold or fool's gold. This is wulfenite, formed from lead and molybdenum. Its crystals can range from red to orange to the yellow we see here.
X: Xenotime
It’s Xeno time! While the name may imply extraterrestrial origins, this xenotime is from Norway. The name actually originates from the greek word for ‘vainglory’, a reference to the original discoverer mistaking it for a new element.
Y: Yarrowite
The blue-green color of this rock comes from yarrowite. Yarrowite is named after Yarrow Creek in Alberta, Canada, the same place this specimen comes from.
Z: Zoisite
The pink lining the edge of the rock is zoisite. Zoisite is a mineral which only rarely forms gems.
Mary Johnson Talc Frog 20Mineralogical and Geological Museum, Harvard University
The Mary Johnson Collection at the MGMH
Mary Johnson is a lifelong mineral rock collector who donated her entire collection to the MGMH in 2019.
All information provided in this story by Aurelio Acevedo. All photographs taken by Kelly Thomas.
