GLOSSARY THE ROCK GARDEN Interesting Rocks from Interesting Places GNEiss – (Pronounced “nice.”) The most common MetamorpHiC Rock – Created when previously of all metamorphic rocks. It is often composed of quartz formed rocks undergo intense heat and pressure, and feldspar, as well as mica, hornblende, or both. It is making them more compact and banded. commonly recognized by its banded appearance. Mineral – A naturally occurring, non-living crystalline GRANiTE – A common, medium-coarse grained, solid with a defined chemical composition and defined intrusive igneous rock. physical properties. IgneouS Rock – Formed by the cooling of magma Rock – Composed of minerals and classified into or the accumulation of materials ejected from volca- three groups (igneous, metamorphic, and sedimentary) noes. Intrusive igneous rocks cool slowly within the based on their formation and composition. Earth while extrusive igneous rocks cool when erupted Sedimentary Rock – Formed when sediments onto Earth’s surface. (fragments of rock, silt, sand, and clay) accumulate and are compacted and cemented into rock. Related Museum Exhibits Dinosaurs: Modeling the Mesozoic Natural Mysteries (Blue Wing, Lower Level) (Blue Wing, Lower Level) Examine fossils and life-size models to get a sense This exhibit focuses on organizing and classifying of how paleontologists compile evidence. While objects and challenges students to observe, there, don’t miss the new exhibit area focusing compare, and sort objects in meaningful ways. on fossil-forming sedimentary rocks. Check out our specimen drawers to learn how scientists classify rocks and minerals. Discovery Center (Red Wing, Level 1) This learning environment is designed for students Take a walk in the Museum’s shady outdoor rock garden! Examine rocks age eight and under and offers an extensive collection and minerals from all over the world and explore their often fiery origins. Can you find for exploring natural history, the physical sciences, the oldest specimen? How about the one from Boston? Which one is your favorite? and technology. Children can test properties of minerals and handle rock specimens in the After your visit, learn about fossils, classification, and other geology-related topics in Natural Mysteries, “Geology Field Station.” Dinosaurs: Modeling the Mesozoic, and the Discovery Center (details on back page). SCP-08-1257 Museum of Science Science Park Boston, MA 02114-1099 mos.org 1 SCHiST pressure on ancient layers of mud. This is a Egyptians believed emeralds gave the wearer Location: Mount Washington, New Hampshire specimen of the bedrock that underlies much powers of prophecy. Today, beryl is important Type: Metamorphic Rock Age: Approx. 390 Million Years of northeastern Boston, including the site of as the source of beryllium, a metal similar to Geologists estimate that Mount Washington the Museum of Science. but lighter than aluminum. began to form about 390 million years ago, 6 GRANiTE 11 LAvA when sand deposited in alternating layers. Location: Grand Canyon Location: Death Valley, California About 375 million years ago, molten rock Type: Igneous Rock Age: One Billion Years Type: Igneous Rock Age: Approx. 60 Million Years pushed between the layers and cooled, This specimen of Precambrian granite is This is a piece of lava from a volcano that was forming the pegmatite vein. The tremendous from the bottom of the Grand Canyon, the once active in Death Valley, the lowest point heat and pressure associated with moun- largest display of river erosion in the world. in North America. Magma is hot, molten rock tain building folded the layers and changed The orange crust you see along the edges of that exists under pressure beneath the Earth’s .VTFVN the sandstone to quartzite, and the shale to &OUSBODF the rock is the result of weathering. surface. Magma that reaches the Earth’s sur- schist. About 10 million years ago, the entire face through vents or fissures is called lava. area was uplifted to form the Presidential 7 GRANiTE Pockets of hot gas produced the cavities that Range of the White Mountains. Location: Italy you see in this sample. Type: Igneous Rock Age: N/A 2 GRANiTE This granite boulder was once a part of Mont 12 Location: New Hampshire Basalt Type: Igneous Rock Age: 360 Million Years Blanc in The Alps. At 15,780 feet, Mont Blanc Location: The Giant’s Causeway (County Antrim, Northern Ireland) Type: Igneous Rock Age: 65 Million Years This is a specimen of the gray granite from is the highest peak in Western Europe. This Geologists cite the Giant’s Causeway as an which the Granite State (New Hampshire) specimen fell in an avalanche down the example of what happens when hot magma gets its name. An intrusive igneous rock, Italian face of Mont Blanc, landed on the from beneath the Earth’s surface erupts and granite is the principal type of rock in the Brenva Glacier, and was slowly carried down- ward by the ice. (Glacial movement ranges pours over the land, cools rapidly, shrinks, Earth’s upper crust and forms the core of then cracks into six-sided columns of basalt, many great mountain ranges. It is particu- from a few inches to a few feet per day.) This an extrusive igneous rock. According to an larly hard because its crystals interlock when rock was collected near the city of Courmay- Irish legend, a giant named Finn MacCool the rock solidifies from a molten state. This eur, Italy. It cooled and hardened slowly, built The Giant’s Causeway between Ireland hardness makes granite highly resistant which accounts for the relatively large crystals and Scotland so that he could walk across the to erosion. Granite is frequently used to on its surface. North Channel without getting his feet wet. %SJWFXBZ construct buildings and monuments as it is 8 Petrified Wood durable and capable of being polished. Location: Petrified Forest National Park, Arizona 13 Gneiss Type: Fossil Age: 200 Million Years 3 Iron Ore Location: Death Valley, California Two hundred million years ago, a tree that Type: Metamorphic Rock Age: 1.7 Billion Years and rounded. When the resulting pebbles, 18 Limestone 20 GRANiTE Location: Marquette, Minnesota cobbles, and boulders accumulate and are Location: Southern Spain Location: Southern Africa Type: Sedimentary Rock Age: 600 Million Years was approximately 200 feet tall grew on the This specimen comes from the bottom of Type: Sedimentary Rock Age: 170 Million Years Type: Igneous Rock Age: 3.2 Billion Years Death Valley. Pegmatite is similar in compo- cemented within a finer-grained matrix, the This jaspilite specimen consists of alternating shores of an Arizona lake. When it fell, it sition to granite, but its grains are coarser. result is an odd-looking rock, a conglomer- This two-ton fragment comes from the This rock could be one of the oldest on Earth. layers of jasper and gray Specularite hematite. became waterlogged, and its wood fibers were Often large crystals of common minerals or ate known as puddingstone. Puddingstone Rock of Gibraltar, whose 1,000-foot cliffs It was taken from a vast exposed area of Jasper, a form of quartz, is the principle type gradually replaced by grains of quartz silica gemstones can be found in irregular patterns underlies much of southwestern Boston, located on the Iberian Peninsula dominate granite in southern Africa. Geologists have of silica found in petrified wood. Specularite that had dissolved in the water. The wood has throughout the pegmatite. with outcrops in Roxbury and the Hammond the entrance to the Mediterranean Sea. The determined its age by measuring how much hematite consists of small flakes that shine since disintegrated, but the tree’s original Pond area. Roxbury Conglomerate is the Rock of Gibraltar has played a significant role of the element rubidium transformed into like mirrors. Look for clues that the rock was shape and growth ring patterns have been 14 GRANiTE Massachusetts state rock. in history. Early humans lived in its caves and the element strontium by radioactive decay— folded after layers of sediment had hardened. preserved. Location: Mount McKinley, Alaska the Phoenicians used it as a landmark when the more strontium present, the older the Type: Igneous Rock Age: 57 Million Years 16 9 Gneiss Gneiss navigating the Mediterranean. This rock is rock. The surface of this rock contains many 4 Gneiss Location: Location: Redwood Falls, Minnesota This 2,000-pound specimen comes from Squam Lake, New Hampshire Location: Mount Washington, New Hampshire Type: Age: chemically similar to seashells and is formed minerals such as feldspar, quartz, chlorite, Type: Metamorphic Rock Age: Approx. 3 Billion Years Metamorphic Rock 400 Million Years Type: Metamorphic Rock Age: 400 Million Years Mount McKinley—at 20,300 feet, the high- under pressure by recrystallization of the apatite, mica, and ilmenite. est peak in North America. Some 57 million The interwoven pegmatite veins in this rock If you want to find out what severe weather Is this the oldest rock in North America? It mineral calcite. years ago, motion in the Earth’s crust caused were formed when molten rock forced its 21 GRANiTE can do to a rock, just look at this specimen originates from a formation of Precambrian metamorphosed granite called Morton gneiss. huge masses of rock to thrust up, forming way along cracks in the metamorphic gneiss 19 Rose QuARTz Location: Aswan Quarries, Egypt from the summit of Mount Washington— Type: Igneous Rock Age: >600 Million Years The rock’s wavy appearance is due to the Mount McKinley and its adjacent Alaska and then solidified. Find the different veins Location: Custer, South Dakota at 6,288 feet Mount Washington is New Type: Mineral Age: N/A Range. Millions of years of erosion reduced and consider which vein formed first. You Egyptians have used red Aswan granite as a England’s highest peak.