Hall of Minerals Hall of Gems

Educator’s Guide

Harry Frank Guggenheim Hall of Minerals Morgan Memorial Hall of Gems

Inside: • Suggestions to Help You Come Prepared • Essential Questions for Student Inquiry • Strategies for Teaching in the Hall • Map of the Exhibition • Online Resources • Correlation to Standards • Glossary

amnh.org/mineralsgems/educators ESSENTIAL Questions

What is a mineral? • Hardness is the degree of resistance to being scratched. It’s determined by rubbing substances of known A mineral is a naturally hardness against minerals and calibrating the results occurring crystalline solid. on the Mohs Scale. Diamond, the hardest mineral, is Crystals are orderly 10 on the scale, while quartz is 7 and talc is 1. arrangements of atoms. Minerals are the building • Fracture and cleavage describe the way minerals break blocks of rocks, which apart. Fracture is the tendency to break along rough make up most of the planet. or curved surfaces, while cleavage is the tendency to Some minerals, like gold break along planes of weakness. Cleavage can help and silver, consist of identify crystal symmetry, which can be useful in telling essentially just one similar-looking minerals apart. element, while others combine two or more. The properties of minerals determine how we can use quartz (Si0 ) Minerals are classified by 2 them. For example, diamond and corundum (ruby) are their chemical compositions, which are defined by used as abrasives because they’re very hard, while soft formulas and by the way the atoms of those chemical and slippery graphite and molybdenite can be lubricants. elements are arranged into crystals. For example, Si02 is the formula for quartz, in which atoms of silicon and How do minerals form? oxygen are arranged in a precise geometry. Gems are Minerals form when minerals that are beautiful, rare, and durable, and which elements crystallize and/ have been cut and/or polished to enhance their beauty. or react chemically with each other in response to What are the properties of minerals? environmental conditions The physical properties of minerals are determined such as changing pres- by their chemical composition and crystal structure. sure and temperature. Scientists magnify, crush, illuminate, scratch, and break They grow by adding jadeite (NaAlSi O ) specimens in order to determine these properties. layers to a starting point 2 6 or surface, and well-formed • Luster is the way a mineral’s surface interacts with crystals most commonly grow in an open space in the light — how brilliant or dull it appears, for example. presence of a fluid. Minerals form everywhere on Earth — Lusters are either metallic (like pyrite) or non-metallic from thousands of meters deep to its surface and (examples include talc, which is pearly; quartz, which is atmosphere — over time frames ranging from seconds glassy; and sulfur, which is earthy). Some minerals (like to millions of years. The conditions under which they graphite) fall in between and are called submetallic. formed tell geologists important things about the planet. For example, jadeite jade probably formed at high pressure where oceanic crust was pushed beneath continental crust, while many rubies were forged where continents collided to create mountain chains.

Why are minerals important? Studying rocks and minerals helps us understand the metallic: non-metallic: submetallic: greater physical world, including Earth’s history and pyrite (FeS2) talc (Mg3Si4O10(OH)2) graphite (C) dynamics. By analyzing a rock’s mineral content and • Scientists crush a mineral by swiping it across a ceramic texture, scientists can learn about the conditions at “streak plate” to reveal the color of its powder — its which it formed. Earth materials are resources. We rely streak. This can help distinguish between minerals with on minerals found in Earth for many products, including the same color but different streak, like hematite metals, ceramics, fillers, semiconductors, glass, and and magnetite. fertilizer. Minerals are also a source of nutrients that all living things require. GLOSSARY COME PREPARED crystal: a naturally occurring, Plan your visit. For information about reserva- symmetrical solid with flat tions, transportation, and lunchrooms, visit surfaces, like a cube, a prism, amnh.org/plan-your-visit. or even a snowflake. Crystals Read the Essential Questions in this guide to are made of atoms arranged in barite (BaSO ) see how the themes in these two halls connect to an orderly, repeating pattern. 4 your curriculum. Identify the key points that you’d deposit: an accumulation or concentration of minerals like your students to learn. laid down by a natural process, such as gravity or the Review the Teaching in the Hall sections of this movement of water, wind, or ice guide for an advance look at the specimens that you and your class will be encountering. element (chemical element): matter composed of a single type of atom. Few elements are found in an Download activities and student worksheets uncompounded, pure form. The periodic table is the at amnh.org/mineralsgems/educators. Designed classification of the chemical elements. for use before, during, and after your visit, these activities focus on themes that correlate to the gem: a mineral that standards. has been cut and/or Decide how your students will explore the halls. polished to enhance diamond (C) its beauty • You and your chaperones can facilitate the visit using the Teaching in the Hall sections. magma: molten rock (formed below Earth’s surface). Magma that reaches the surface is called lava. • Students can use the student worksheets to explore the halls on their own or in small groups. mineral: a natural solid with a crystal structure and a • Students, individually or in groups, can use specific chemical composition copies of the map to choose their own paths. mineralogy: the study of minerals, or what mineralogists — including crystallographers, mineral physicists, and crystal chemists — do CORRELATIONS TO THE NEXT GENERATION Mohs Scale of Hardness: a system for determining the resistance of a mineral to being scratched, with 1 being SCIENCE STANDARDS the softest (talc) and 10 the hardest (diamond) Science Practices • Asking questions • Developing and using models • Planning and carrying out rock: a naturally occurring solid made of one or more investigations • Analyzing and interpreting data minerals. Rocks make up most of Earth’s crust. • Using mathematics and computational thinking • Constructing explanations • Engaging in argument sediments: small fragments of mineral or rock that are from evidence • Obtaining, evaluating, and broken off, carried, and deposited by wind, water, or ice communicating information vein: a distinct body of Crosscutting Concepts • Patterns • Cause and effect: crystallized minerals that mechanism and explanation • Scale, proportion, and occupies a fissure quantity • Systems and system models • Energy and matter: flows, cycles, and conservation • Structure within a rock mass and function • Stability and change

Disciplinary Core Ideas • PS1.A: Structure and Properties of Matter • PS1.B: Chemical Reactions • ESS2.A: Earth Materials and Systems • ESS2.B: Plate gold and quartz vein Tectonics and Large-Scale System Interactions in metamorphic rock • ESS3.A: Natural Resources HARRY FRANK GUGGENHEIM HALL OF MINERALS Teaching in the HALL

This hall presents hundreds of striking specimens collected from around the world. Almost everything on display came out of Earth looking the way it does here. The guided explorations below are designed around two sections of the hall: Properties of Minerals and Mineral Forming Environment. The numbers correspond to stops on the map.

PROPERTIES OF MINERALS

Scientists perform a range of measurements to determine the crystal structure of minerals, as well as their physical, chemical, and optical properties. Some minerals are easy to identify, but most require multiple tests. In this section, students will explore four cases to see how mineral properties can be determined and measured.

1a. Atoms, space lattices, and crystals: A mineral’s 1d. Optical properties of minerals: Color is an important characteristic crystal structure is determined by how its optical characteristic, but can vary within mineral types atoms fit together. Have students compare the models and overlap across others. Streak — the color of the in the center of the case to the crystal shapes of mineral residue left when the mineral is scraped against a rough specimens to the right. Ask them to explore how atomic surface — can help distinguish minerals from one another. arrangements in different minerals are expressed in Draw students’ attention to hematite (#48). Like many actual crystals, and how bonded groups repeat in three minerals, it is black, but its streak is distinctly red. Pyrite dimensions to make crystals. (#44) is gold, but its streak is black.

1b. Physical properties of minerals: These different crystal structures result in a huge variety of physical properties — even when minerals are made of the same element or elements. Have diamond students compare two carbon-based minerals, diamond and graphite. How do their crystal structures and physical properties differ? (In diamonds, atoms are closely packed in all directions, making it very hard. Graphite’s atoms graphite are closely packed along one plane streak plates show the colors of various mineral powders (#42-51) only, which makes it softer.) Have students explore a variety of characteristic properties (hardness, cleavage, Luster is another optical property. Minerals can display fracture, tenacity, specific gravity) by reading the labels either a metallic luster (#32-36) or non-metallic luster and observing the samples to the right. (remaining specimens in the left-hand case). The way light passes through some minerals can also help with 1c. Chemical properties of minerals: These properties identification. reflect the chemical elements that minerals are made of. Scientists use chemical tests to distinguish between minerals with similar physical properties. They determine how minerals react under different conditions, such as exposure to heat, water, or acids. Have students explore different ways to identify minerals with chemical tests. minerals with a metallic luster (#32-36) Point out that halite (large specimen on the left) and calcite (#12) share many Show students the halite and calcite specimens (#73, 74), physical properties, but and draw their attention to the mounting brackets. How halite dissolves in water do they look different when viewed through the calcite and calcite in hydrochloric sample? (The calcite sample shows double refraction of acid. the light passing through it, making it appear that the halite (NaCl) bracket has double bars.) calcite (CaCO3) MINERAL FORMING ENVIRONMENTS

Minerals are the building blocks of rocks, and form as rocks form. Mineral crystals are typically small, but sometimes grow to large sizes. In this section, students will explore minerals that form in different environments within Earth as well as at or near its surface, and see, for example, that the same mineral may form in different environments. Specimens that may be familiar to students, such as those found on the NYS Earth Science Reference Tables, are indicated at each stop.

WITHIN EARTH 2e. Hydrothermal and metamorphic environment: When minerals form from other minerals: Certain minerals result when two different environments overlap. 2a. Metamorphic environment: Conditions of high Have students explore what minerals temperature, high pressure, or both can rearrange formed under these conditions near the atomic structures of minerals within rocks, New York City. Point out different transforming them into other minerals. In this specimens such as copper (#15), environment, the minerals never become a liquid. pyrite (#20), and magnetite (#38). copper (Cu) Point out minerals that formed in this way, such as pyrite (#9, 27), talc (#13), and graphite (#18). AT OR NEAR EARTH’S SURFACE When minerals form in igneous rock deep in Earth: When minerals crystalize in surface water: 2b. Magmatic environment: Mineral crystals grow as 2f. Evaporite environment: Lakes in warm and dry magma cools and hardens into solid rock. The particu- climates may contain water with a high mineral content lar minerals depend on the chemical composition of because elements dissolved from surrounding rock the magma, its depth, and the temperature when it formations wash into them. As the water evaporates, crystallizes. Students can observe minerals that the concentration of dissolved elements becomes so make up gabbro rock (#11, on left), rich in calcium high that they crystalize into minerals. Draw students’ and magnesium, which form at higher temperatures. attention to halite (#1, 6) and gypsum (#13). Minerals that make up granite rock (#3, on right), rich When minerals form in igneous rocks at the surface: in silicon and aluminum, form at lower temperatures. 2g. Volcanic environment: When lava erupts onto 2c. Pegmatite environment: When magma becomes Earth’s surface, it typically forms mineral crystals as almost entirely crystalized, rare crystals can form it cools and hardens. In addition, secondary minerals and grow to large sizes. This happens because certain often grow in the numerous pockets and holes that elements normally in lower abundance become con- form in the rock when it cools. (All of the minerals in centrated, and also because volatile components build the first volcanic case are from a basaltic rock 20 up. The volatiles create vapor pockets that allow larger miles west of New York City.) Minerals are also often crystals to form. Point out quartz (#9, 10, 14 in the first deposited around active volcanoes. For example, case); zircon (#8 in the second case), magnetite (#15), sulfur (#4 in the right-hand case), crystallizes from and hematite (#33); beryl (#10-12 in the third case) and escaping sulfur dioxide and hydrogen sulfide gases. rose quartz (#17); and stunning examples of topaz (#3) Show students hematite (#2) and calcite (#18). and beryl (#8) in the last case of large crystals. When minerals form in flowing water: When metals are deposited in rocks: 2h. Sedimentary environment: Water and wind 2d. Hydrothermal environment: As water with high weather surface rock and mineral materials into small- concentrations of metals moves through rock, it can er pieces, which are then transported and deposited leave rich deposits. This creates veins containing met- at new sites. When these sediments react chemically als such as gold, copper, and zinc, both deep in Earth’s with water, new minerals develop. Heavier minerals crust and closer to its surface. Hotter temperatures at like gold will sink, separate, and concentrate, forming a greater depth result in certain types of deposits, like placer deposit. In the left-hand sedimentary case, have pyrite (#16 in hypothermal, #25 in mesothermal), while students look at gold (#3, 10) and zircon (#6, 13); in the shallower, cooler temperatures (epithermal case) result center, sulfur (#7) and calcite (#10); and on the right, in deposits of gold (#2) and silver (#21). hematite (#15), pyrite (#20), and magnetite (#24). ONLINE Resources

FROM THE MUSEUM Earth OLogy amnh.org/explore/ology/earth Hands-on activities and articles for kids 7 and up, including: • Grow Rock Candy: use sugar to make and compare crystals • Jade: find out why a mineralogist thinks jade is so special • If Rocks Could Talk: meet six rocks from Mexico, Scotland, and even outer space!

Microminerals amnh.org/belskymicrominerals An annotated, interactive guide to the Hall’s Howard Lee Belsky Memorial Exhibit of Microminerals (microscopic-sized mineral crystals).

Profile: George Harlow amnh.org/explore/amnh.tv/(watch)/meet-the-scientists/profile-george-harlow A video portrait of crystal chemist, jade specialist, and Museum curator George Harlow.

Gold amnh.org/exhibitions/past-exhibitions/gold Explore a variety of topics related to this soft and lustrous metal, prized across history and around the world. Includes links to this exhibition’s Educator’s Guide and other resources.

Zircons: Time Capsules from the Early Earth amnh.org/explore/science-bulletins/zircons Travel to Greenland and a zircon-making lab in New York State to learn why these intriguing mineral crystals are the basis of new hypotheses about Earth’s first 500 million years. Nine-minute video.

In Glittering Gems, Reading Earth’s Story Mineral Matters nyti.ms/11fzxNb sdnhm.org/archive/kids/minerals This New York Times article explains what gems tell This San Diego Natural History Museum site for kids geologists about the history of our planet. explains how to identify minerals, build a collection, and grow crystals. Includes mineral FAQs and games. Mineralogy 4 Kids mineralogy4kids.org Smithsonian Minerals Collection Developed by the Mineralogical Society of America, this collections.mnh.si.edu/search/ms site includes sections on minerals in the home; mineral A searchable photographic database of 100 mineral groups, properties, and identification; and lots of games. specimens from the Smithsonian’s collection.

CREDITS Photo Credits Cover: Guggenheim Hall of Minerals, gems, zircon, © AMNH/R.Mickens; prehnite, ©AMNH/C.Chesek. Funding for the Educator’s Guide has been provided through Essential Questions: all photos, © AMNH. Glossary: all photos, © AMNH. Come Prepared: peridot the generous support of The Louis Calder Foundation. crystal, © AMNH. Teaching in the Exhibition (Minerals): all photos, © AMNH/C.Chesek. Online Resources: Earth OLogy, © Eric Hamilton; malachite, George Harlow, zircon expedition, © AMNH; gold, © AMNH/J.Beckett. Teaching in the Exhibition (Gems): all photos, © AMNH/C.Chesek.

MAP of the Halls

SYSTEMATIC MINERALOGY INTRO TO ESTHETIC MINERALOGY MINERALS

2h 2a California Gold 2g 2b 1a 1d 2f PROPERTIES OF MINERAL MINERALS FORMING ENVIRONMENTS 2c NATURE OF COMMON MINERALS 1b 1c MINERALS

2e 2d MICROMINERALS

ENERGY AND 3c 3b MINERALS FOREVER GOLD VIDEO

GUGGENHEIM HALL OF MINERALS MORGAN HALL OF GEMS

Properties of Minerals Mineral Forming Environments 3a Gem pocket 1a Atoms, space lattices, 2a Metamorphic environment 3b Sapphires and crystals 2b Magmatic environment 3c Star of India 1b Physical properties 2c Pegmatite environment 3d of minerals Quartz 2d Hydrothermal environment 1c Chemical properties of minerals 2e Hydrothermal and metamorphic environment 1d Optical properties of minerals 2f Evaporite environment 2g Volcanic environment 2h Sedimentary environment

An array of precious and ornamental stones — some uncut, polished, or in elaborate settings — is on exhibit in this hall. Drawn from the Museum’s collection of more than 100,000 minerals and gems, specimens are organized by mineral group and include precious metals. Several cases feature decorative objects and jewelry, which span three millennia and many cultures.

GUIDED EXPLORATIONS 3d. Quartz: Some minerals, like garnets and Tip: Bring small flashlights so students can see how diamonds, have the same specimens react to beams of light. name as their gemstones. In other cases, the same 3a. Gem pocket: Minerals are the mineral can give rise building blocks of rocks, and form to different gemstones as rocks form. Mineral crystals because its color varies. are typically small, but sometimes So purple quartz is called grow to large sizes. This is a amethyst, and yellow quartz is called citrine. Have recreation of a natural, crystal- students observe the way different quartz specimens filled cavity that was found in the vary in color and clarity, and compare uncut (natural) mountains of California. Have specimens to cut ones. students find all seven examples of large mineral crystals: tourmaline, albite, quartz, Have students locate the February and November kunzite, morganite, lepidolite, microcline. birthstones in this case. Then, invite them to find the others around the hall and to note which minerals 3b. Sapphires: A few minerals are used as gems in (in parentheses) give rise to multiple gems. their natural crystal form. Most, however, are shaped January: garnet (garnet) August: peridot (olivine) and polished to bring out their sparkle, brilliant color, February: amethyst (quartz) September: sapphire and/or unusual texture. Gems that are transparent, like March: aquamarine (beryl) (corundum) these sapphires, are April: diamond (diamond) October: tourmaline normally faceted: cut with May: emerald (beryl) (tourmaline) a machine that polishes June: moonstone (feldspar) November: citrine (quartz) small, flat windows (called July: ruby (corundum) December: topaz (topaz) facets) at regular intervals and exact angles. This maximizes light reflected by the stone, highlighting its optical properties and causing it to What Makes a Gem? sparkle. Invite students to observe the visual effects of Gemologists use certain properties, some listed below, different types and numbers of facets. to determine the quality of a gem.

3c. Star of India: Stones that Color: depth (not too dark or pale), uniformity, fluorescence are not completely transparent Clarity: transparent, translucent, opaque are usually shaped and polished Hardness: resists scratching (7+ on Mohs scale) into cabochons: a smooth dome Durability: will not shatter, crack, or cleave Brilliance: high index of refraction, high luster shape. This shows off the stone’s Special optics: iridescence (play of colors), cat’s eye or color or surface properties, as star effects with opals and star sapphires like this famous 563-carat stone. The Did you know? Carat karat. (Or carrot.) ball-like Star of India has stars on both sides. This pattern Carat is the standard unit of weight (mass) for gems is caused by tiny fibers of the mineral rutile, which reflect — not to be confused with karat, the unit of measure- incoming light in a three-dimensional pattern called ment of gold purity. However, both are based on the asterism and also give the gem its milky quality. carob seed, an ancient measure of weight.