Geological Star Trek Review – “Arena”

Captain Kirk fights a Gorn in the 1967 TOS episode “Arena” – you can see Vasquez Rocks in the background.

Sulfur, niter (saltpeter) and carbon, as coal and as crystalline diamond, save Captain Kirk’s life in the 1967 TOS episode “Arena.”

When a remote outpost of the Federation is attacked by an unknown enemy, the Enterprise pursues the fleeing vessel, inadvertently entering a sector of space controlled by the Metrons, a race with powerful psychic powers. Kirk, transported by the Metrons to a desolate planetoid, is forced into a battle against the captain of the Gorn ship – a reptile-like creature protected by an almost indestructible armored skin.

The planetoid displays a rich geologic diversity. Kirk mentions finding ruby corundum. He uses niter (saltpeter), sulfur, and coal he finds to make gunpowder for use in a primitive cannon, and diamonds as projectiles (here – judging from the crystal shape – likely quartz was used as film prop). After injuring the Gorn, Kirk spares his life to the surprise of the Metrons.

There are almost 5.000 known mineral species, yet the vast majority of rocks are formed from combinations of a few common minerals, like feldspars, quartz, amphiboles, micas, olivine, garnet, calcite, and pyroxenes. We still know little about other worlds. Over 300 minerals have been identified in meteorites, 130 minerals were discovered so far on Mars and 80 on Earth’s Moon.

By convention, the names of terrestrial minerals (a crystalline combination of one or various elements) end with the suffix -ite, the denominations of elements with the suffix – ium, -um, -on, -gen, or -ine. This nomenclature is not always applied in Star Trek.


  • De FOURESTIER, J. (2005): The Mineralogy of Star Trek. Axis, Vol.1(3): 1-24

Geological Movie Review – “Alien”

When the movie “Alien” was released in 1979, it quickly terrified audiences worldwide. Its unexpected mix of classic horror and science-fiction elements got at first mixed reviews, however, over the years Alien had come to be regarded as one of the best horror-science-fiction films ever made.”Alien” screenwriters Dan O’Bannon and Ronald Shusett based parts of their script on various older science-fiction movies and tales, like “At the Mountains of Madness”, a science-fiction/horror story published by American author H.P. Lovecraft in 1936. In the story, a team of scientists is hunted and killed by ancient creatures resembling fossil animals. Lovecraft apparently based this part of his story on the real discovery of fossil archaeocyathids in Antarctica made in 1920 by geologist William Thomas Gordon. Archaeocyathids are an extinct group of sponge-like creatures believed to be among the oldest animals ever to live on Earth.

Hans Rudolf Giger, Swiss surrealist artist, architect and industrial designer, was hired to create all forms of the Alien featuring in the film, from the egg to the adult. Giger created various versions of the alien life-cycle, like a gigantic egg nest, replaced in the final movie with an egg silo inside a derelict spaceship. The eggs were directly inspired by female reproductive organs, slightly modified to avoid censorship. The facehugger, a parasite attaching to the head of its victim to incubate an embryo, is based on the bones and muscles of a human hand and male genitalia, its springlike tail was added to emphasize its quick movements. The parasitic life-form was an idea of Ronald Shusett. Shusett suggested that one of the crew members be implanted with an alien parasite to explain how the alien life-form, discovered at first as an egg in a derelict alien spaceship, came on board of the mining spacecraft Nostromo. The parasite bursts from the chest of its victim and soon the crew has to deal with the fast-growing life-form hiding in the air vents of the spaceship. The design of the chestburster and the full-grown xenomorph (alien-shaped thing) is based on Giger’s “Necronom IV“, an artwork created in 1976. The surrealist drawing shows a female figure composed of different parts of insects, parts of vertebrates and even fossils. Giger used the fossils of 300 million-year-old crinoids, commonly called sea lilies, on display in the Aathal dinosaur museum as a source of inspiration.

A petrified crinoid. Similar fossils inspired the creature featured in the successful “Alien” saga.

The earliest known crinoids date back to the Ordovician (some 450 million years ago). Their remains are very common in the fossil record, forming rocks like limestone or dolostone. The skin of echinoderms, including sea cucumbers, sea urchins, crinoids, brittle stars and starfish, is covered with tiny ossicles made of calcium carbonate forming a protective, yet flexible, outer shell. In a similar way, Giger’s Alien is protected by a silicon-based external skeleton. This outer shell is also very useful to contain the acid blood of the creature. Concept artist Ron Cobb added the acid blood as a defense mechanism, making it impossible to kill the Alien without damage to the crew or the spaceship.

In the sequel “Aliens” a team of space marines enters an Alien hive, the walls resembling Goethite, Grube Eisekaute, Bad Marienberg, Germany.

The life-cycle of the Alien from egg to queen (as introduced in the sequel) resembles the life-cycle of real animals, the Ichneumonidae. The Ichneumonidae is a wasp family preying on insects. An adult female wasp will lay her eggs within a host through a process known as ovipositing. The eggs will grow and develop into larvae, which will feed on their host from the inside-out. Somewhere along the way the host will actually die or be kept in a state very near death until, finally, the little wasp spins a cocoon around and-or within its host, eventually emerging as an adult wasp. A horrified Charles Darwin famously mentions in a letter sent in 1860 to his friend, the botanist Asa Gray, the parasitoid wasp:

» I cannot persuade myself that a beneficent and omnipotent God would have designedly created the Ichneumonidae with the express intention of their feeding within the living bodies of caterpillars… «

In their natural environment, these wasps play important roles in regulating the populations of their insect hosts, and have been used in agricultural crops to control caterpillar pests. Dolichogenidae xenomorph is a parasitoid wasp species named in 2018 after the xenomorph, as “the wasp is also black and shiny like the Alien.”

The graphic representation of the “perfect organism” earned the visual effects team of “Alien” a well-deserved Academy Award.

Geological Star Trek Review – “The Devil in the Dark”

The 1967 Star Trek episode “The Devil in the Dark” was written in just three days by screenwriter Gene L. Coon. Despite the rushed production, this first season episode is almost always included in every “best of” list. Trekkies value the story and message, as Kirk finds a peaceful solution to a conflict with an unknown life-form, but also love some remarkable classic scenes and lines, including “Pain! Pain! Pain!” and “I’m a doctor, not a bricklayer!” This episode holds also a special place in many geologist’s hearts as it features a lot of geo-babble.

It is one of the rare episodes starting not on board of the Enterprise, but in the mines of Janus VI. According to federation classification Janus VI is a type-E rocky planet with an iron core, similar in size to Earth but just 1.3 billion years old and apparently without atmosphere or life on the surface. It’s rich in minerals and elements, like gold, uranium, platinum, cerium and the fictional pergium. Mining an extraterrestrial world is still fiction, but science shows that it may be profitable. Asteroids are rich in platinum, iridium, palladium and gold. One hundred tons of rock from an asteroid might today be worth more than 9,000 dollars, compared to just 60 dollars worth the same amount of terrestrial rocks. Estimated 5,000 to ten millions of asteroids can be found near Earth and companies are already dreaming of future prospecting and mining spaceflights. Mining asteroids would not necessarily benefit Earth, as bringing the ore to Earth would be costly, but might benefit nearby colonies, outposts or industrial complexes. In “Devil in the Dark” it is mentioned that “dozen planets depend on you for pergium.” Pergium is somehow needed for common power generators (but apparently outdated, as Chief Engineer Scotty hasn’t seen such a thing in over twenty years), providing energy not only for the colony on Janus VI but other worlds.

The mining colony in the episode was successfully operating for over fifty years but after the miners opened up a new level deep within the planet suddenly a monster started to attack and kill people. The Enterprise sends Kirk, Spock and McCoy for help. Spock during a meeting with the chief engineer Vanderberg, the administrative head of the mine, notes a strange sample in the office:

“It’s a silicon nodule. There are a millions of them are down there. No commercial value.”

“But a geological oddity, to say the least. Pure silicon?”

“A few trace elements. Look, we didn’t call you here so you could collect rocks.”

Later Spock and Kirk are able to injure the supposed monster and recover what seems to be living tissue, however, a close inspection reveals the tissue to be “fibrous asbestos, a mineral.” Asbestos is indeed a silicate mineral, which is found as aggregates of thin fibrous crystals on Earth.

Byssolithe, a type of silicate, forms fibrous crystals.

After this discovery Spock speculates that the supposed monster is an alien life-form, not based on carbon compounds as on Earth, but on silicon. The strange silicon nodules destroyed by the clueless miners are eggs and the creature was just defending her children. After Spock joins with the mind of the creature a peaceful agreement is found between the miners and the alien. The miners will not hurt or kill the creatures and the creatures will allow the miners to use their tunnels to mine the deeper pergium-rich layers of the planet (and so become rich). The Horta, as this alien is named in the series, use a sort of hot acid to melt their tunnels in the solid rocks.

The silicon-based life-form as depicted in Star Trek is surprisingly scientifically accurate. In life as we know it only ten elements play a mayor role. Carbon is one of the most important elements, followed by oxygen, nitrogen, hydrogen, potassium, calcium, magnesium, iron, phosphorus and sulfur. Carbon is common in the universe but relatively rare on Earth. Strangely silicon is quite common in Earth’s rock, but plays only an insignificant role in biological processes. Some microorganisms, like radiolarians and diatoms, use silaffins and silica-hydrogels to build their tiny shells. Siliceous sponges use silicon to support their body by constructing a framework composed of tiny needles of silicon dioxide. However, all those organisms use silicon only to build their skeleton, not in their living tissue or metabolism.

Carbon, despite its relative rarity on Earth, has some important advantages for life on Earth. It can form stable and complex macromolecules within the range of terrestrial temperatures. Living bacteria are found on Earth in 240°F hot springs and on frozen rocks of Antarctica, thriving at -60°F . Atomic bounds between carbon-carbon, carbon-oxygen and carbon-hydrogen atoms are strong and the formed molecules are soluble and stable in water. Water is so important for carbon-based life as it´s a perfect environment for molecules to react with each other, resulting in a life-sustaining metabolism. Silicon, like carbon, can form stable bounds with itself and other elements like carbon, nitrogen, phosphorus, oxygen, sulfur and many metals. Such silanes can form sheets, chains, tubes and even complex three-dimensional frameworks. In theory silanes could be combined to form organelles of a living cell and even reactive molecules sustaining an alternative metabolism.

That said, silicon shows a very strong affinity to oxygen and hydrogen. On Earth the tissue of a silicon-based life-form would slowly react with the oxygen of the air and the hydrogen in the water, corroding and killing the creature. Doctor McCoy even mentions this fact in the episode. However, Spock notes that the creature comes from within the planet, where suitable conditions for silicon-based life might exist.

Silicon-life would need an oxygen-free atmosphere, an environment with no water and an alternative liquid for its metabolism. Possible alternative solvents that may work include liquid methane and ethane, but also sulfuric and hydrocyanic acid.  The acid could explain the (fictional) ability of the Horta to “digest rock” and to “tunnel” so quickly “for nourishment” through the planet. As such compounds are unstable at higher temperatures, the silicon-based life-form would best thrive in a very cold environment.

Could such life really exist? Unfortunately we don’t know for sure and the Horta is never again mentioned in the original series. Maybe this question will be answered by future generations, when humanity encounters life, but not as we know it. How will we react? In “The Devil in the Dark,” the first response was fear and hate, in the end overcome by knowledge and emphaty – a message in the best tradition of Star Trek.

Geology and Alpine-Type Fissures

Swiss professor of philosophy Horace-Bénédict de Saussure (1740-1799) was one of the first naturalists to collect observations and measurements in the field. He did so by traveling the Alps and climbing various mountains, among others the Mont Blanc, with 4.810 meter the highest peak of the Alps. During his ascent, he recorded the physiological reactions of his body to the increased elevation, measured air temperature and described the rocks which compose the mountain. One of De Saussure’s guides onto the peak of Mont Blanc was Jacques Balmat, a local chamois hunter and Strahler. A strahler is a crystal seeker, so named after the Strahlen, the shining quartz crystals. The granite of Mont Blanc is famous for its Alpine-type fissures, hosting sometimes spectacular crystals.

The crystal seeker Jacques Balmat, painting by Henry Lévèque.
Reconstruction of an Alpine fissure in Mont Blanc granite, with quartz, flourite and chlorite crystals.

Most common are gash fractures formed during the Alpine orogenesis some 25 to 15 million years ago. Below 500°C rocks like gneiss, schist and amphibolite tend to react brittle to tectonic deformation. Permeable to circulating fluids, in the open fissures and at temperatures of 600 to 100°C crystals will start to grow.

Kluft – an Alpine-type fissure in the field. from “Mineralklüfte und Strahler der Surselva” by Flurin Maissen (1950). A stiff layer will tend to deform, flattened and stretched to the point that it “necked”, opening a gash fracture between boudins. Thin layers will wrap around this point, partially forming quartz veins. More deformed, the layers will tend to weather more easily.

Almost 80% of the Alpine-type minerals comprise feldspar, chlorite, calcite, and quartz. Typical Alpine-type minerals are actinolite, apatite, dolomite, epidote, flourite, hematite, titanite, rutile and zeolithe – more than 140 minerals are known from Alpine-type fissures found in the Eastern Alps.

Alpine-type fissure in greenschist with a typical mineral paragenesis of adularia , quartz and chlorite.

De Saussure’s son – Nicolas Théodore de Saussure – will in 1792 name the mineral dolomite, giving the Dolomites their modern name.

How to Identify Feldspar in the Field

Feldspars are by far the most common minerals, constituting nearly 60% of all terrestrial rocks. They are important in both magmatic (formed by crystallization from molten magma) and metamorphic rocks (formed by alteration of older rocks by heat and pressure over time). It’s only in sedimentary rocks that feldspars are relatively rare, as the crystals easily break (having a perfect cleavage) and tend to decay and erode in contact with water.

Feldspar is a name that comprises a series of aluminosilicate minerals with three end members: orthoclase (potassium feldspar K[AlSi3O8]), albite (sodium feldspar Na[AlSi3O8]) and anorthite (calcium feldspar CaAl2Si2O8). Albite and anorthite form a completely miscible series called plagioclase. Albite and orthoclase can form a complete miscible series at higher temperatures.

As there is miscibility between the various members of the feldspar group, exact feldspar identification in the field, without chemical analysis, can be difficult (to impossible).

Orthoclase is a common constituent of most granites and other felsic igneous rocks and often forms huge crystals and masses in pegmatite. Euhedral crystals are commonly elongate with a tabular appearance, colorless to white in appearance; however, traces of iron-oxides can cause greenish, greyish-yellow or reddish-pink coloration. Orthoclase often displays Carlsbad twinning and light is reflected differently by the crystal faces of the two intergrown crystals. Luster is vitreous to pearly.

1-6 cm large orthoclase (K-feldspar) in the Terlaner ryhodacitic porphyry (a subvolcanic rock). The crystal displays characteristic Carlsbad twinning and secondary reddish coloration by iron-oxides.

Plagioclase is the most important feldspar in basaltic magmatic rocks. On fresh surfaces colorless to whitish, on eroded surfaces often colored greenish-yellowish by traces of decomposing sericite, chlorite and epidote (however, reddish coloration by iron-oxides also possible). Virtually identical to orthoclase when fresh, shows less well developed twinning (polysynthetic twinning with lamellar crystals intergrowth, visibile only on microscopic scale) and generally forms smaller crystals. In granitoid rocks, plagioclase is composed mostly of albite (70 to 50%), in basaltic rocks (like diorite, gabbros and basalt), with an abundance of calcium, anorthite prevails with 60 to 90%.

Auer Formation, former pyroclastic flows deposits, with a matrix of sanidine (potassium feldspar) crystals, reddish-pink plagioclase crystals and quartz.

Feldspar has a relatively high mineral hardness of 6 after Mohs and can barely be scratched with the blade of a pocket knife or geological hammer. In metamorphic rocks, like orthogneiss (metamorphic granitoid rocks), it can form characteristic porphyroclasts, harder mineral grains surrounded by a groundmass of finer grained crystals, referred to colloquially as “Augen” (=eyes).

Reiner Orthogneis, Altkristallin, Rein in Taufers.

Weathered alkali-feldspar (orthoclase-albite series) will decay to white, crumbly argillaceous minerals, like kaolinite. Plagioclase decays to argillaceous minerals or fine-grained aggregates of colourless to grey sericite (mica variety).


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