GEOL 1101 – The Dynamic Earth Review Questions & Answers for Lecture Test 1

GEOL 1101 – The Dynamic Earth Review Questions for Lecture Test 1 Topic 1 – Introduction to Geology 1. What is geology? How does it differ from earth sciences? Answer: Geology is a discipline that is focused on the study of solid earth materials (terrestrial or extraterrestrial). Geological studies generally focus on characterization of the processes that produce minerals or rocks. Earth sciences focus on characterization of the solid and non-solid earth (broader scope than geology). 2. What are some examples of disciplines within earth sciences? List four examples, and provide an overview of what each discipline is concerned with. Answer: Examples of disciplines within the earth sciences include: ● Oceanography (study of oceans) ● Limnology (study of lakes) ● Climatology (study of climate) ● Meteorology (study of weather) 3. What are some examples of disciplines within geology? List four examples, and provide an overview of what each discipline is concerned with. Answer: Sub-disciplines of Geology (not exhaustive) ● Key geologic disciplines include: ● Hydrogeology ○ Concerned with the study of groundwater: its occurrence, movement, distribution, and quality. ○ Focuses on the interaction between groundwater and geological formations, as well as the exploration and management of groundwater resources. ● Engineering geology ○ Applies geological principles to civil and mining engineering projects. ○ Involves assessing geological factors like rock and soil stability, groundwater conditions, and seismic hazards to ensure the safety and feasibility of construction projects. ● Petroleum geology ○ Specializes in the exploration, extraction, and production of oil and gas resources. ○ Involves identifying and assessing geological structures and formations that may contain hydrocarbon reservoirs, using techniques such as seismic imaging and well logging. ● Mining geology ○ Focuses on the discovery, extraction, and processing of mineral resources from the Earth's crust. ○ Involves assessing the geological characteristics of ore deposits, designing mining operations, and managing environmental impacts associated with mining activities. ● Environmental geology ○ Studies the interactions between humans and the geologic environment, with a focus on environmental hazards, natural resource management, and pollution remediation. ○ Involves assessing geological hazards such as landslides, earthquakes, and floods, and developing strategies for mitigating their impacts. ● Planetary geology

○ Explores the geology of other planets, moons, and celestial bodies in the solar system. ○ Involves studying planetary surfaces, landforms, and geological processes to understand their formation and evolution. ● Structural geology ○ Investigates the deformation and arrangement of rock layers and geological structures in the Earth's crust. ○ Focuses on understanding the forces and processes that shape the Earth's crust, including folding, faulting, and mountain building. ● Geochemistry ○ Studies the chemical composition and processes of Earth materials, including rocks, minerals, soils, and water. ○ Involves analyzing the distribution and behavior of chemical elements to understand geological processes such as mineral formation, weathering, and the cycling of elements through the Earth's systems. ● Mineralogy ○ Focuses on the study of minerals, including their composition, structure, properties, and occurrences. ○ Involves identifying and classifying minerals, as well as investigating their roles in geological processes and their economic significance. ● Petrology ○ Investigates the origin, composition, and textures of rocks, including igneous, sedimentary, and metamorphic rocks. ○ Involves studying the processes of rock formation, alteration, and transformation to understand the Earth's history and evolution. ● Geophysics (overlap with physics) ○ Applies principles of physics to study the Earth's interior structure, composition, and processes. ○ Involves using techniques such as seismic imaging, gravity and magnetic surveys, and electrical resistivity measurements to investigate subsurface features and geological phenomena. 4. How does geology affect us? List three reasons why geology matters to society. Answer: i) Geologic hazards (e.g., earthquakes, landslides) endanger everyone. Geology can be used to predict where they will happen! ii) Locate the natural resources that we need to sustain our current way of life, including: ● Water (i.e., groundwater resources) ● Critical minerals (Li-bearing minerals that can be used to make batteries) ● Precious (gold) and base metals (iron and nickel) ● Hydrocarbons (oil, gas, methane) iii) Global Climate Change geology can measure and help us understand a dynamic changing environment and how these changes will impact us on an annual or decade'el or perhaps out even 100 years from now. How those changes will affect our everyday ecosystem where we live, our rivers and streams, the trees and the environment around us. 5. What is a sphere? Provide mathematical, practical, and possession-based definitions. A sphere is most frequently defined as follows: Answer:

of other gases, including sulfur dioxide (SO2) and water vapor (H2O). Jupiter - (ChatGPT Answer) - hydrogen (H2) and helium (He), similar to the composition of the Sun. It also contains trace amounts of methane (CH4), ammonia (NH3), and other hydrocarbons. Saturn - (ChatGPT Answer) - Saturn's atmosphere is primarily composed of hydrogen (H2) and helium (He), with traces of methane (CH4), ammonia (NH3), and other hydrocarbons Mercury - (ChatGPT Answer) - oxygen (O2), sodium (Na), hydrogen (H2), helium (He), and potassium (K). However, its atmosphere is so sparse that it's often considered to be virtually nonexistent compared to the other planets. 9. What is the biosphere? How is it related to the geosphere, hydrosphere, and atmosphere? Answer: The biosphere includes Earth’s organisms, as well as any organic matter not decomposed. The chemical composition of the Earth’s atmosphere is quite different from what would be found on a lifeless planet! ● Free oxygen in Earth’s atmosphere is the result of 3 billion years of photosynthesis and is therefore a product of life ! ● A modern day coral reef. This is where the biosphere, hydrosphere, geosphere, and atmosphere come together! 10. What is the anthroposphere? Answer: The anthroposphere is any part of the nature system that has been modified by humans, for human purposes , or as a result of human activities . 11. What is a system? Why is it important to define systems when performing a scientific study? Answer: A system is any portion of the universe that can be isolated from the rest of the universe for the purpose of observing and measuring changes. A system is only a concept – you choose the limits for the convenience of your study - defining the nature of the boundary is one of the most important defining features of a system. 12. What are the three different kinds of systems? Sketch them out, and explain how they differ from one another. Answer: Three basic kinds of systems: (A) Isolated systems – systems that do not interact with their surroundings (B) Closed systems – systems that do not allow transfer of matter in or out (C) Open systems – systems that do allow transfer of matter across system boundaries

13. Provide an overview of the various scales that are considered when addressing geologic problems. Answer: Examples of different spatial scales: ● Earth - Sun distance: 149,600,000 km ● Earth diameter: 12,742 km ● Mount Everest elevation: 8,848 m ● Range of atomic radii: 30 - 300 pm (one trillionth of a metre!) Examples of different temporal scales : ● Age of Earth: 4.5 billion years ● Orbital cycles: 21,000 - 100,000 years ● Earthquake duration: seconds to minutes 14. Provide an overview of the various changes that are studied as a part of a geologic investigation. Answer: Almost all geologic studies are focused on trying to explain change. Studied changes include: ● Mineral formation (elements form minerals, minerals change to other minerals) ● Rock formation (minerals form rocks, rocks change to other rocks) ● Ocean and continent formation (spatial and temporal changes to both entities) ● Climate changes (warm periods, cold periods, dry periods, wet periods) ● Biological changes (evolution, mass extinction) Topic 2 – Formation of the Universe and the Earth 1. What is a paradigm? Answer: Paradigms are prevalent ideas of a society, they change through time and differ between cultures . The way that people have explained different aspects of the natural world and how they fit into it can be called religion , natural theology or theoretical geology . 2. What is the geocentric model of the universe? What ancient group proposed it? Answer: Earth was at the centre of the universe, earth is surrounded by a layer of air and fire followed by the Moon, Mercury, Venus, the Sun, Mars, Jupiter, and Saturn. All celestial bodies and related features lie within the globe of the stars. Greek philosophers began to argue about the structure of the universe. 3. What is the heliocentric model of the universe? What scientist is often credited with proposing it? Answer: Heliocentric sun at the centre of the universe, discussions dominated by Copernicus.published in 1543. 4. What is the big bang theory? How long ago did it occur? Answer: premise of the Big Bang is that the universe expanded outwards from an initial state of high density and temperature. Big Bang event is thought to have occurred ~15 billion years ago 5. How do nebulas form? Why do they have a disk - like shape?

9. What are the three types of meteorites? Which types of meteorites are thought to resemble the early earth? Answer: Meteorites can be grouped into three categories: (1) stony meteorites; (2) iron meteorites; and (3) stony iron meteorites. Stony meteorites have a rocky composition, while iron meteorites have a metallic composition. Stony iron meteorites have mixed composition, since these meteorites are thought to have a composition that is similar to that of the early Earth (particularly in the core of the Early earth). Question from slides - Have we found any meteorites in Western or Northern Canada? If so, where were they found? Yes, meteorites have been found in Western and Northern Canada. Here are a few notable examples: 1. Tagish Lake Meteorite: The Tagish Lake meteorite fell in the vicinity of Tagish Lake, British Columbia, in January 2000. Fragments of the meteorite were recovered from the lake's frozen surface and surrounding areas. The Tagish Lake meteorite is a carbonaceous chondrite, a type of meteorite that contains primitive materials from the early solar system. 2. Lost Hammer Meteorite: The Lost Hammer meteorite was discovered in 2011 near the shores of the Arctic Ocean in Western Nunavut, Canada. It is an iron meteorite and is notable for being one of the few meteorites discovered in the Canadian Arctic. 3. Alberta Meteorite: Various meteorites have been found in Alberta, including the Bruderheim meteorite, which fell near the town of Bruderheim in 1960, and the Innisfree meteorite, which fell near the town of Innisfree in 1977. 4. Saskatchewan Meteorite: Meteorites have also been found in Saskatchewan, such as the Battle River meteorite, which fell near the Battle River in 2008, and the Elstow meteorite, which fell near the town of Elstow in 2004. These are just a few examples, and there may be other meteorites that have been discovered in Western and Northern Canada as well. Meteorite discoveries are typically reported to scientific authorities and studied for their scientific significance. 10. Which other planets in our solar system possess geospheres? Which ones do not? Answer: (ChatGPT answer) In our solar system, all the terrestrial planets possess geospheres, which are solid rocky bodies with distinct layers including a crust, mantle, and core. These terrestrial planets are: ● Mercury ● Venus ● Earth ● Mars The gas giants, on the other hand, do not possess geospheres in the same way. These planets are: ● Jupiter ● Saturn ● Uranus ● Neptune While they do have solid cores, their outer layers are composed mainly of gases and do not exhibit the same layered structure as terrestrial planets.

11. Explain how nebular cloud differentiation occurs. Answer: Heavier material (i.e., dust) is drawn into the centre of the solar system, while lighter material (gas, ice) is blown away to the outer regions. 12. What are the main factors that contributed to the heating and melting of the early Earth’s interior? List each factor, and explain how each mechanism works. Answer: Three major factors caused the heating and melting in the early Earth’s interior: 1. Collisions (kinetic energy → heat) 2. Compression 3. Radioactivity of elements (e.g., uranium, potassium, or thorium) 13. How did the Earth’s interior become so differentiated? Explain. Answer: As the Earth began to form, dense materials such as iron became concentrated near the core. Materials that were not as dense started to form an outer layer. 14. How did the moon form? Explain using a diagram. Answer: Moon is thought to have been formed after a giant Mars - sized body (called Theia) struck the early Earth. The material from the impact was ejected into orbit and the material accreted together to form the Moon. 15. What are the four main zones of the Earth’s interior? List them, and explain their characteristics. Answer: Crust (solid phase; Si-Al-rich continental and Fe-Mg-rich oceanic varieties) ■ Continental crust thickness = 20-80 km; Oceanic crust thickness = 5-10 km ○ Mantle (solid phase; Fe-Mg rich, plastic flow) ○ Outer Core (liquid phase; Fe-Ni-rich) ○ Inner Core (solid phase; Fe-Ni-rich) Topic 3 – Plate Tectonics Lithosphere?

Answer: (ChatGPT) Roberto Mantovani was an Italian geologist and seismologist who made significant contributions to the early development of the theory of continental drift and plate tectonics. His main contribution was in proposing a mechanism for continental drift based on the concept of mantle convection . The Earth's internal heat causes convection currents in the mantle, leading to the movement of tectonic plates. He suggested that as the mantle material rises due to heat from the Earth's core, it spreads laterally beneath the lithosphere, causing the continents to drift apart. This idea laid the groundwork for our understanding of the driving forces behind plate tectonics. While his specific mechanism for mantle convection was not entirely accurate, Mantovani's ideas contributed to the development of the broader theory of plate tectonics, which is now widely accepted in the geological community. His work helped pave the way for further research into the dynamic processes that shape the Earth's surface and interior. 6. Who is Frank Bursey - Taylor? What was his main contribution to plate tectonics? Answer: (ChatGPT) Frank Bursley Taylor was an American geologist who proposed the theory of continental drift in 1908, which was a precursor to the modern theory of plate tectonics. He suggested that the continents were once part of a single supercontinent , which he called Pangaea , and that they had drifted apart over time. 7. Alfred Wegener proposed continental drift to attempt to try and explain how continents and oceans formed. Explain the three pieces of evidence that Wegener used to support his continental drift hypothesis. Answer: In 1912, a meteorologist named Alfred Wegener proposed that the formation of landmasses and oceans was tied to a phenomenon he termed “continental drift” ● Hypothesis was based on evidence such as conformable coastlines and similar fossil assemblages and rock types from continent to continent 8. Wegener’s continental drift hypothesis was widely criticised by other scientists. List three reasons why. Answer: WEGENER COULD NOT PROVIDE A MECHANISM TO EXPLAIN HOW THE CONTINENTS MOVED! 1. Shorelines constantly change over time (how good of a fit could we expect?) 2. Plant seeds could have travelled by other means (winds, ocean currents) 3. Ancient animals could have found other ways to reach other continents 9. Explain, using a diagram, how changes in the Earth’s magnetic field are recorded in rocks. Answer: ● Note: This diagram shows the Earth’s magnetic field in its present day orientation relative to the north geographic pole. Question from lecture slides: Has the orientation of the Earth’s magnetic field stayed fixed over millions of

years? (ChatGPT Answer) The orientation of the Earth's magnetic field has not stayed fixed over millions of years. In fact, the Earth's magnetic field has undergone numerous reversals throughout its history, where the magnetic north and south poles have switched places. These reversals are known as geomagnetic reversals or polarity reversals. Evidence? Studies of the magnetic properties of rocks, particularly volcanic rocks, which record the direction and intensity of the Earth's magnetic field at the time they formed. When lava solidifies, the magnetic minerals within it align themselves with the Earth's magnetic field, effectively "locking in" the magnetic orientation of that time. Analyzing the magnetic properties of rocks of different ages, scientists have been able to construct a record of past geomagnetic field behavior. This record shows that geomagnetic reversals have occurred repeatedly over geological time, with no fixed pattern in terms of timing or frequency. (From textbook page 750) The last two reversals of Earth’s magnetic field were at the beginning of the present Brunhes normal chron (0.78 Ma), and at the end of the Jaramillo normal subchron (0.90 Ma). Figure 8.5.3 The last 5 Ma of magnetic field reversals (Textbook page 308) For reasons that are not completely understood, the magnetic field decays periodically and then becomes re-established. When it does re-establish, it may be oriented the way it was before the decay, or it may be oriented with the reversed polarity. Over the past 250 Ma, there have been a few hundred magnetic field reversals, and their timing has been anything but regular. The shortest ones that geologists have been able to define lasted only a few thousand years, and the longest one was more than 30 million years, during the Cretaceous (Figure 9.3.2). Figure 9.3.2 Magnetic field reversal chronology for the past 170 Ma. The first 5 Ma of the magnetic chronology are shown in more detail in Figure 8.5.3, although the time scale is in the opposite direction in that figure. Changes in Earth’s magnetic field have been studied using a mathematical model, and reversals have been shown to take place when the model was run to simulate a period of several hundred thousand years. The fact that field reversals took place shows that the model is a reasonably accurate representation of the Earth. According to the lead author of the study, Gary Glatzmaier, of University of California at Santa Cruz: “Our solution shows how convection in the fluid outer core is continually trying to reverse the field but that the solid inner core inhibits magnetic reversals because the field in the inner core can only change on the much longer time scale of diffusion. Only once in many attempts is a reversal successful, which is probably the reason why the times between reversals of the Earth’s field are long and randomly distributed.” A depiction of Earth’s magnetic field lines during a stable period and during a reversal is shown in Figure 9.3.3. To read more about these phenomena see Glatzmaier’s Geodynamo website.

12. What was the final piece of evidence that scientists needed to prove that seafloor spreading was a plausible explanation for the formation of continents and oceans? Answer: (Textbook P. 334 -335) Collection of magnetic data from the oceans continued in the early 1960s, but still nobody could explain the origin of the zebra-like patterns. Most assumed that they were related to variations in the composition of the rocks—such as variations in the amount of magnetite—as this is a common explanation for magnetic variations in rocks of the continental crust. The first real understanding of the significance of the striped anomalies was the interpretation by Fred Vine, a Cambridge graduate student. Vine was examining magnetic data from the Indian Ocean and, like others before, he noted the symmetry of the magnetic patterns with respect to the oceanic ridge. At the same time, other researchers, led by groups in California and New Zealand, were studying the phenomenon of reversals in Earth’s magnetic field. They were trying to determine when such reversals had taken place over the past several million years by analyzing the magnetic characteristics of hundreds of samples from basaltic flows. As discussed in Chapter 9, it is evident that Earth’s magnetic field becomes weakened periodically and then virtually non-existent, before becoming re-established with the reverse polarity. During periods of reversed polarity, a compass would point south instead of north. The time scale of magnetic reversals is irregular. For example, the present “normal” event, known as the Bruhnes magnetic chron, has persisted for about 780,000 years. This was preceded by a 190,000-year reversed event; a 50,000-year normal event known as Jaramillo; and then a 700,000-year reversed event (see Figure 9.3.3).

In a paper published in September 1963, Vine and his PhD supervisor Drummond Matthews proposed that the patterns associated with ridges were related to the magnetic reversals, and that oceanic crust created from cooling basalt during a normal event would have polarity aligned with the present magnetic field, and thus would produce a positive anomaly (a black stripe on the sea-floor magnetic map), whereas oceanic crust created during a reversed event would have polarity opposite to the present field and thus would produce a negative magnetic anomaly (a white stripe). The same idea had been put forward a few months earlier by Lawrence Morley, of the Geological Survey of Canada; however, his papers submitted earlier in 1963 to Nature and The Journal of Geophysical Research were rejected. Many people refer to the idea as the Vine-Matthews-Morley (VMM) hypothesis. Vine, Matthews, and Morley were the first to show this type of correspondence between the relative widths of the stripes and the periods of the magnetic reversals. The VMM hypothesis was confirmed within a few years when magnetic data were compiled from spreading ridges around the world. It was shown that the same general magnetic patterns were present straddling each ridge, although the widths of the anomalies varied according to the spreading rates characteristic of the different ridges. It was also shown that the patterns corresponded with the chronology of Earth’s magnetic field reversals. This global consistency provided strong support for the VMM hypothesis and led to rejection of the other explanations for the magnetic anomalies. 13. Who is John Tuzo Wilson? What was his main contribution to plate tectonics? Answer: John Tuzo Wilson was a professor of geophysics at the University of Toronto. Throughout his life, he suggested that the Atlantic Ocean had opened and closed multiple times, giving rise to the Wilson Cycle model. Wilson also deduced the origin of hotspot volcanism, and also explained how transform faults form. 14. What are the names of the twelve major lithospheric plates?

Answer: They always move on top of the magma however the way they shift and move has changed over time. Topic 4 – Minerals 1. What is an atom? What components make up an atom? List and describe each component. Answer: Atoms consist of a nucleus that contains protons (P+) and neutrons (N) . Electrons (e-) orbit the nucleus in orbitals. If electrons are lost/gained, atoms become ions. 2. What is an ion? How does it differ from an atom? Answer: If electrons are lost/gained, atoms become ions. 3. What is an isotope? Why are isotopes important? Answer: Isotopes are two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons, resulting in a different atomic mass. 4. What is a mineral? Answer: A mineral is any substance that: (1) Occurs naturally (manufactured substances like steel are not minerals!) (2) Generally forms as a result of inorganic processes (some minerals form organically!) (3) Is solid at the Earth’s surface (4) Possesses a characteristic crystal structure (in other words, atoms form a definite repeatable pattern) (5) Possesses a (mostly) definite chemical composition (some changes may occur within the limits of the structure) 5. How are minerals used? Provide three applications that specific minerals are used for in everyday life. Answer: Aluminum – (1) packaging, transport, building, (2) Beryllium – gemstones, fluorescent lights, (3) Copper – electric cables, wires, switches, (4) Iron – buildings, cars, magnets, (5) Lithium – Li- ion batteries! Specific minerals: (1) Feldspar – glass, ceramics, (2) Calcite – toothpaste!, (3) Gypsum – drywall, (4) Halite – table salt! 6. What are the main ways that minerals form? List the different mechanisms, and provide an example of the setting in which these mineral formation mechanisms tend to occur. Answer: Precipitation from a solution, precipitation from gaseous emanations, metabolism of an organism deep-water environments, weathering, metamorphism (heat, pressure and fluid interaction) 7. What are the key mineral groups that we are covering in this course? List the different groups, and provide two examples of characteristic minerals from each group. Answer:

Group Common Examples Oxides Hematite (iron oxide; Fe 2 O 3 ), corundum (aluminum oxide, Al 2 O 3 ) Sulphides Galena (lead sulphide, PbS), pyrite (“fool’s gold”, iron sulphide, FeS 2 ) Sulphates Gypsum (calcium sulphate, CaSO 4 ·H 2 O), barite (barium sulphate, BaSO 4 ) Halides Halite (sodium chloride; NaCl), fluorite (calcium fluoride, CaF 2 ) Carbonates Calcite (calcium carbonate, CaCO 3 ), dolomite (calcium-magnesium carbonate, CaMg(CO 3 ) 2 ) Phosphates Apatite (Ca 5 (PO 4 ) 3 (OH)), turquoise (CuAl 6 (PO 4 ) 4 (OH) 8 ·5H 2 O) Native minerals Gold (Au), graphite (C), diamond (C), sulphur (S), copper (Cu) Silicates Quartz (SiO 2 ), feldspar (sodium-aluminum silicate, NaAlSi 3 O 8 ), olivine (iron or magnesium silicate, (Mg,Fe) 2 SiO 4 ) Why are these minerals so common? 8. What are the most common rock - forming minerals? List them. Answer: Over 4,000 different minerals are known at present (new minerals are being discovered all the time!). However, interestingly enough, most rocks are made up of less than a dozen minerals Common rock-forming minerals: ● Quartz ● Feldspar (group) ● Muscovite (white mica) ● Biotite (black mica) ● Calcite ● Pyroxene ● Olivine ● Amphibole (group) ● Iron oxides (e.g., magnetite and hematite) ● Pyrite 9. What is a polymorph? Why are polymorphs important? Answer: Polymorph - Same chemical formula, but different structure.

Non-metallic minerals may look as if light will not pass through them, but if you take a closer look at a thin edge of the mineral you can see that it does A non-metallic mineral has a shiny, reflective surface, then it is called “glassy.” Calcite (CaCO 3 ) If it is dull and nonreflective, it is “earthy.” Kaolinite (Al 2 (OH) 4 Si 2 O 5 ) Other types of non-metallic lustres are “silky,” Gypsum (CaSO 4 ·2H 2 O) “pearly,” Muscovite (KAl 2 (AlSi 3 O 10 )(F,OH) 2 ) and “resinous.” WAXY -Variscite (AlPO ·2(H O)) ₄ ₂ GREASY - Opal (SiO 2 ·2(H O)) ₂ Lustre is a good diagnostic property since most minerals will always appear either metallic or non- metallic. There are a few exceptions to this (e.g., hematite). 13. What is mineral hardness? How was it originally determined? Answer: Hardness is one of the most important (and diagnostic) properties that a mineral possesses. The hardness of a mineral is found by trying to scratch it using an object that has a known hardness . 14. Which minerals on the hardness scale are harder than a streak plate? Answer: Friedrich Mohs came up with a list of 10 reasonably common minerals that had a wide range of hardnesses. These minerals are shown in Figure 2.6.3, with the Mohs scale of hardness along the bottom axis. In fact, while each mineral on the list is harder than the one before it, the relative measured hardnesses (vertical axis) are not linear. For example apatite is about three times harder than fluorite and diamond is three times harder than corundum. Some commonly available reference materials are also shown on this diagram, including a typical fingernail (2.5), a piece of copper wire (3.5), a knife blade or a piece of window glass (5.5), a hardened steel file (6.5), and a porcelain streak plate (7). These are tools that a geologist can use to measure the hardness of unknown minerals. For example, if you have a mineral that you can’t scratch with your fingernail, but you can scratch with a

copper wire, then its hardness is between 2.5 and 3.5. And of course the minerals themselves can be used to test other minerals. 15. Which minerals on the hardness scale are softer than a copper penny? Answer: Talc, gypsum and calcite 16. What is crystal habit? Do all mineral specimens display excellent examples of crystal habit? Answer: A possibility that minerals will form distinctive crystal shapes if they formed slowly and are not crowded out by other pre-existing minerals.