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October 13, 2020


Bring out your inner geologist and take the Geologist Tongue Twister Audio or Video challenge! 

First, do an audio or video recording of you reading the Tongue Twister. Second, feature a rock or mineral from your rock collection or go outside and find yourself a rock; they are everywhere!  

Be sure to hashtag your video #earthscienceweek and #USGSrocks

This Earth Science week (and beyond) we challenge you to a geology tongue twister. Tell us about your rock specimen. Do you know what your rock type is? There are three groups, Igneous, Sedimentary, and Metamorphic.  Is it a rock, mineral, or fossil? Even if you don’t know what kind of rock you have, say something about your rock, mineral, or fossil.  Teachers, use this page anytime your class subject is on science with a focus on geology.


A Geologist Tongue Twister: Geologists collect - slate and shale slabs - sparkling sperrylite - stinky sulfur - silvery silicon
A tongue twister on geology featuring a few rocks and minerals in our everyday lives. Tongue Twister by Donna Pizzarelli.  Photo of Sperrylite by Chip Clark, Smithsonian Mineral Sciences Collections (NMNH 170395). (Public domain.)

Line by Line about our featured rocks and minerals.  

Geologists collect …


Slate and Shale slabs

Slate and shale may look similar, they are both stones flattened into parallel sheets, which is called "foliation, hence the confusion.  However, slate is a metamorphic rock which make it much stronger and harder than shale which is a sedimentary rock.


Slate is used for landscaping and construction, such as for pathways and roofing tiles. Before wipe-off boards, most schools used slate blackboards. Slate was also used by American Indians and Alaska Natives in their art, regalia, and tools.


1905 classroom showing students using slate blackboards.
Grade school classroom in 1905 showing students writing on slate blackboards with smaller 'slates' on their desks.  Chalk also comes from rocks. Originally made of the mineral chalk, today's blackboard, pastel, and sidewalk chalks are primarily made of the mineral gypsum. Photo Courtesy of IMLS Digital Collections and Content (Public domain.)
Left, painting of Seminole Indian wearing silver gorget (amulet). Right photo of two gorets made of slate.
Before the introduction of metals including steel and silver, Native Americans used slate, shells, and other natural materials for their amulets and gorets.  Here Seminole warrior, Os-ce-o-lá, The Black Drink, is wearing a silver gorget. In 2019, USGS scientists helped to provide a detailed photographic record of slate gorgets and fragments found along the banks of the Patuxent River in Maryland.(Public domain.)



Shale is a source material in the ceramics industry to make brick, tile, and pottery. Shale can be crushed and heated with limestone to make cement for construction. Today, shale interest is in the petroleum industry, which uses fracking to extract oil and natural gas from oil shale.

Image shows a sample of cannel coal on a rock background
Cannel coal is a type of bituminous coal that is also sometimes referred to as a type of oil shale. It's name likely came from the word "candle." Cannel coal was once used as a source for kerosene.  (Credit: Donna Pizzarelli, USGS, Public domain.)


Sparkling Sperrylite

Platinum arsenide, sperrylite, is a rare mineral and essential ore of platinum. Platinum is a precious metal commodity used in jewelry, dental work, and as an alloy with other metals for electrical contacts, wires, and laboratory instruments. For example, an alloy of platinum and cobalt is used to produce permanent magnets that create a persistent magnetic field. 


Mineral: Sperrylite
Photograph of Sperrylite by Chip Clark, Smithsonian National Mineral Collection (Public domain).

Stinky Sulfur

Yes, sulfur is smelly and typically compared to the smell of rotten eggs.  Sulfur is both a chemical element and a mineral.  Sulfur in its mineral state does not smell, but certain organosulfur compounds make it stink.  Sulfur is most often found near volcanoes and hot springs. Sulfur is used in fertilizer, pharmaceuticals, antibacterial soaps, and acne creams. Sulphur is also very flammable and is used in matches and in fireworks made from gunpower. Other minerals and chemicals are used to make firework colors.


image related to volcanoes. See description
Telephoto view of sulfur deposits at one of the several fumaroles on the north wall of Halema‘uma‘u. USGS photo by D. Swanson, 08-14-2019. (Public domain.)



Silvery Silicon

Silicon, very abundant in the Earth’s crust, is produced from the source min­eral quartz.  Silicon is one of many minerals used in the display, electronics, circuitry, batteries, and speakers in your mobile device.



Close up of Silicon Carbide
Mineral: Silicon Carbide(composed of silicon and carbide)Primary Commodity: Silica (abrasive)Primary Commodity Uses: Just as their name implies, abrasives are used to abrade, clean, etch, grind, polish, scour, or otherwise remove material(Credit: Scott Horvath, USGS. Public domain.)



Silica Crucible and Glass Desiccator
Geochemists use platinum, silica, and ceramic crucibles, shown here in a glass container called a desiccator.  Silica is used because it is resistant to extremely high temperatures and because it is chemically inert. Silicon, linked up with a pair of oxygen molecules as silicon dioxide, is known as silica. (Credit: Donna Pizzarelli, USGS, Public domain.)

Sedimentary Sandstone

Sandstone is a sedimentary rock composed of sand-size grains of mineral, rock, or organic material. Sandstone was used in ancient times as a building material for temples, buildings, and homes.  A relatively soft stone, artists used it to carve ornamental fountains and statues.


Image: Sandstone Peaks in Zion National Park
Zion Canyon is characterized by its dramatic sandstone peaks. (Credit: Alex Demas, USGS. Public domain.)

Mesa Verde National Park in southwestern Colorado was established in 1906 to preserve and protect the artifacts and dwelling sites, including the famous cliff dwellings, of the Ancestral Puebloan people who lived in the area from about A.D. 550 to A.D. 1300. In 1978, the United Nations designated the park as a World Heritage Site. The geology of the park played a key role in the lives of these ancient people. For example, the numerous (approximately 600) cliff dwellings are closely associated with the Cliff House Sandstone of Late Cretaceous age, which weathers to form deep alcoves. In addition, the ancient people farmed the thick, red loess (wind-blown dust) deposits on the mesa tops, which because of its particle size distribution has good moisture retention properties. The soil in this loess cover and the seasonal rains allowed these people to grow their crops (corn, beans, and squash) on the broad mesa tops. From USGS Pamphlet to accompany Scientific Investigations Map 3224, Surficial Geologic Map of Mesa Verde National Park, Montezuma County, prepared in cooperation with the National Park Service.


Cliff Palace and massive sandstone cliffs
Cliff Palace is protected from the elements by the massive sandstone cliffs of the Cliff House Sandstone. Dark-colored lines, painted upon the rocks by desert varnish, form when heavy metals such as manganese oxides are dissolved and re-precipitated onto the rocky surface. (Credit: Annie Scott, USGS . Public domain.)

Sandstone block shown here contains a large fossil palm leaf.
Most fossils occur in sedimentary rocks including shale, limestone and sandstone. The sandstone block shown here contains a large fossil palm leaf, found at the Coryell Coal mines in Colorado. “Fossil plants and animals became important tools for establishing the geologic age of rocks and correlating them from one region to another.” This photo was taken in front of a group of miners. Newcastle. Garfield County, Colorado in 1907.  Photograph and quote on page 19 from ‘Images of the U.S. Geological Survey, 1879-1979” celebrating the USGS’s 100th anniversary.   (Credit: H.S Gale. Public domain.)

Shards and Slivers of Shiny Schist

Schist is a medium-grade metamorphic rock formed from mudstone or shale.  Like shale, it is not a very strong stone.  Schist's shine comes from their composition of muscovite and biotite; these are called mica schists.  Schist does not have many uses, but the gemstones they hold formed during the metamorphism of schist are very valuable.  One such gemstone is the garnet that is used as an abrasive for and replacement for industrial sandblasting.   Like the red ruby, the garnet has been used in jewelry for centuries.


Close up of Garnet Schist
Mineral: Garnet SchistPrimary Commodity: GarnetPrimary Commodity Uses: Garnet is mostly used for abrasives, water filtration, and some electronics (Credit: Scott Horvath, USGS. Public domain.)

(If you need to cut-n-paste)

A Geologist Tongue Twister

Geologists collect

slate and shale slabs

sparkling sperrylite

stinky sulfur

silvery silicon

sedimentary sandstone

and shards and slivers

of shiny schist


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