Rocks at DMR Educational Rock and Mineral Garden

 

Description of Rocks at DMR Educational Rock and Mineral Garden

Rock Gardens and Displays DMR Educational Rock and Mineral Garden

“Building The Blue Ridge”Virginia has a very interesting and varied geologic history that spans nearly one and onehalf billion years. Rocks exposed throughout the Commonwealth reflect a long and complex geologic history that resulted in unique and exotic geologic terrines. Across Virginia, the landscape exhibits all rock types: igneous, metamorphic, and sedimentary. The Educational Rock and Mineral Garden was designed to display a portion of Virginia’s geological variety. The educational
display will contribute to the understanding of the geology and rock types found throughout the Commonwealth.
* Ma = million years ago
Black and Gray Limestone - Augusta County 1. Black and Gray Limestone – Augusta County Donated By: Rockydale Quarries Corporation, Staunton Lime Company Black and gray, thinly-layered limestone; layering reflects rhythmic changes in depositional environment. Lincolnshire Formation, Ordovician (440 – 505 Ma*).
Biotite-Quartz-Feldspar Gneiss 2. Tightly-folded, Biotite-Quartz-Feldspar Gneiss Chesterfield County Donated By: Vulcan Materials Company, Dale Quarry Isoclinally folded, biotite, quartz, and feldspar gneiss interpreted as sedimentary rocks metamorphosed during Grenville-age regional metamorphism (approx. 900 – 1200 Ma). Maidens gneiss; original rock Middle Proterozoic (900
– 1600 Ma).
Feldspar Granofels Albemarle County 3. Biotite – Feldspar Granofels Albemarle County Donated By: Martin Marietta Aggregates, Red Hill Quarry Medium- to coarse-grained, aggregate of biotite, hornblende, quartz and monocrystalline feldspar, with little or no lineation/foliation. Interpreted as primary igneous assemblage that crystallized from a magmatic melt (granite-like) which was later metamorphosed. Related rocks have been radiometrically dated at approximately 1004 Ma. Basically a porphyroblastic augen gneiss; Middle Proterozoic (900 – 1600 Ma).
Ribbon Limestone Wythe County 4. Ribbon Limestone Wythe County Donated By: Austinville Limestone Company, Inc. Thinly layered limestone and calcite, with feathery texture; probably diagenetic deformational features. Patterson member (“Ribbon Rock”) of the Shady Dolomite, Cambrian (505 – 544 Ma).
Hydrothermally-altered Diorite (Furtharwite) Culpeper County 5. Hydrothermally-altered Diorite (Furtharwite) Culpeper County Donated By: Cedar Mountain Stone Corporation, Mitchells Plant Hydrothermal fluids recrystallized and mineralized a zone within diabase. Sample contains byssolite (white), prehnite (light green), epidote (pistachio green), and feldspars (white, tan to pink). Intrusive diabase, Jurassic – Triassic (146 – 245 Ma).
Gabbro Culpeper County 6. Gabbro Culpeper County Donated By: Cedar Mountain Stone Corporation, Mitchells Plant Coarse grained, composed of amphibole crystals (black) and plagioclase feldspar (gray). Large size amphibole crystals indicates a slow cooling rate from the original magma. Magma intruded into sediments in the Culpeper Basin; Jurassic – Triassic (146 – 245 Ma).
Orthoquartzite Wythe County 7. Orthoquartzite Wythe County Donated By: Wythe Stone Company, Lots Gap Quarry Spotted sedimentary quartzite showing rounded areas of iron-stained, loose, large sand grains. Erwin Formation, (equivalent to Antietam Formation) of the Chilhowee Group, Cambrian (505- 544 Ma).
Sandstone with Assorted Fossils Frederick County 8. Sandstone with Assorted Fossils Frederick County Donated By: Unimin Corporation, Gore Plant Sandstone showing diverse community of fossils, mostly brachiopods (Costispirifer & Eospirifer), gastropods, crinoids, trilobites, and pelecypods. Oriskany Formation, Devonian (360 – 410 Ma).
Fractured Limestone Rockbridge County 9. Fractured Limestone Rockbridge County Donated by: Rockbridge Stone Products, Inc., Glasgow Plant Limestone exhibiting fractures filled with calcite. Small vugs are filled with calcite crystals. Shady Formation, Cambrian (505 – 544 Ma).
Limestone with Stromatoporoid Fossils Highland County 10. Limestone with Stromatoporoid Fossils Highland County Donated By: Miracle Ridge Limestone Fossilized limestone showing stromatoporoids, crinoids, and bryozoans. Stromatoporoids are extinct benthic, marine, sponge-like organisms. Tonoloway Formation, Silurian (410 – 440 Ma).
Deformed, Pink and Gray Marble Appomattox County 11. Deformed, Pink and Gray Marble Appomattox County Donated By: Rockydale Quarries Corporation, Appomattox Lime Company Light-pink and dark-gray, laminated, fine- to medium-grained marble. Archer Creek Marble Member of the Mt. Athos Formation, Late Proterozoic to Cambrian (744 – 505 Ma).
Storm Deposited Limestone Highland County 12. Storm Deposited Limestone Highland County Donated By: Miracle Ridge Limestone Limestone showing depositional environment of storm related rip-up of carbonate strata. Tonoloway Formation, Silurian (410 – 440 Ma).
Pegmatite Chesterfield County 13. Pegmatite Chesterfield County Donated By: Vulcan Materials Company, Dale Quarry Coarsely crystalline rock, with pink potassium feldspar, gray quartz, biotite and muscovite. Result of very slow cooling of granitic melt. Pegmatites similar to this one have been radiometrically dated at approximately 260 Ma. Intrusive into pre- Cambrian age Maidens gneiss, Pennsylvanian (286 – 325 Ma).
Red Shale and Siltstone Rockbridge County 14. Red Shale and Siltstone Rockbridge County Donated By: Rockbridge Stone Products, Inc., Glasgow Plant Reddish-brown, shale and siltstone showing ancient horizontal worm burrows, trail markings, and mud cracks. Rome Formation, Cambrian (505 – 544 Ma).
Anorthosite Amherst County 15. Anorthosite Amherst County Donated By: Boxley Aggregates, Piney River Plant Specimen is non-foliated, and extremely coarse grained. Mineralogy consists of yellowish-white anorthite feldspar, clinopyroxene, apatite and ilmenite. Patches and blobs of dark reddish-brown rutile are evident. Commercially marketed as “Virginia Aplite”. Radiometrically dated at 1045 Ma. Roseland Anorthosite, Middle Proterozoic (900 – 1600 Ma).

The Oldest Moon Rocks — “Apr 21, 2004 … Anorthosites, rocks composed almost entirely of plagioclase feldspar, are the oldest rocks on the Moon. They appear to have formed when …” The Moon, Earth’s major satellite — “The early Moon was probably molten but, when it cooled, low-density plagioclase crystals grew within the liquid and floated to the surface where they collected to form a thick layer of anorthosite rock.”

Amphibole Gneiss Halifax County 16. Amphibole Gneiss Halifax County Donated By: Vulcan Materials Company, South Boston Quarry Medium-grained, light-gray to light-pink, foliated, gneiss. Light-pink to white feldspar augen (blobs) are common in a gray hornblende-biotite groundmass. Foliation is cut by both pink and white pegmatite veins. Metavolcanic rock, Ordovician (440 – 505 Ma).
Blue Quartz Madison County 17. Blue Quartz Madison County Donated By: Rev. Henry D. Aylor Quartz can be found in a variety of colors: white, blue, pink, green, and clear. Blue quartz from the Blue Ridge Mountains is valued as a decorative stone and for jewelry. Blue quartz is found in the older basement rocks of the Blue Ridge Province. Probable age, around Grenville time; Middle Proterozoic (900 – 1600 Ma).
Blue Quartz Madison County
White Quartz Albemarle County 18. White Quartz Albemarle County Donated By: David Warren Silica in the form of quartz occurs in lenticular veins throughout most of Virginia. The veins formed where fluids moved through rock fractures. A few of the larger veins have been mined. Quartz can be used as a flux in the steel industry and as decorative stone. Probable age of Ordovician – Cambrian (440 – 544 Ma).
Deformed Gneiss with Blue Quartz Vein Rappahannock County 19. Deformed Gneiss with Blue Quartz Vein Rappahannock County Donated By: Lisle Carter and Jane Livingston Segregation-layered, migmatitic (partially-melted), quartzo-feldspathic, polydeformed biotite gneiss. Blue quartz veins are common. Radiometrically dated at 1081 Ma. Making this one of Virginia’s oldest rock formations. Flint Hill Gneiss, Early Proterozoic (1600 – 2500 Ma).
Petrified Logs Henrico County 20. Petrified Logs Henrico County Donated By: Vulcan Materials Company, Mideast Division These logs were buried in the sediments of the James River near Curles Neck. After burial, silica replaced the rotting wood, preserving the structure of the tree. Likely from Cretaceous (146-65 Ma) sediments, overlain by Pleistocene (11,000 years – 1.8 Ma) fluvial sand and gravel . NO. 2/3 VIRGINIA MINERALS 15
Slate Buckingham County 21. Slate Buckingham County Donated By: Buckingham – Virginia Slate Corporation Dark gray, lustrous, very-fine-grained, highlyfoliated slate. Composed of chlorite, muscovite, plagoiclase, quartz, and biotite. Cleaves readily along foliation. Used for roofing shingles, patio stone, laboratory table tops, and road aggregate. Arvonia Slate, Ordovician (440 – 505 Ma).
Calcite Vein in Dolostone/Limestone Augusta County 22. Calcite Vein in Dolostone/Limestone Augusta County Donated By: John Marr and Roy Sites Gray dolostone/limestone with a large fracture filled with calcite crystals from fluids moving through the rock (post 505 ma). Beekmantown Formation, Ordovician (440 – 505 Ma).
Calcite Appomattox County 23. Calcite Appomattox County Donated By: Rockydale Quarries Corporation, Appomattox Lime Company Fluids circulating through fractures in a dominantly carbonate rock sequence produced large zones of homogenous calcite (post 505 Ma).
Soapstone Nelson County 24. Soapstone Nelson County Donated By: New World Stone Company Medium- to fine-grained, bluish gray to grayish green, moderately schistose soapstone. Composed of talc, chlorite, serpentine, amphibole, magnetite and pyrite. It is a soft rock with high heat-retaining capabilities. Can be sawed and carved into desirable forms. Favorite of sculptors. Can also be used to construct stoves and cabinet tops. Part of a metamorphosed, mafic igneous complex, Cambrian – Late Proterozoic (505 – 900 Ma).
Siltstone with Mud Cracks Culpeper County 25. Siltstone with Mud Cracks Culpeper County Donated By: Martin Marietta Aggregates, Culpeper Quarry Interbedded maroon siltstone and brownish shale showing mud cracks and trail markings. Balls Bluff Siltstone, Triassic (208 – 245 Ma).
Granodiorite with Pegmatite Vein Mecklenburg County 26. Granodiorite with Pegmatite Vein Mecklenburg County Donated By: Vulcan Materials Company, Mecklenburg Quarry Light-gray to white, medium-grained, foliated granodiorite gneiss. Sample contains granitic and pegmatitic injection veins. Deformation and injection veins indicate that this rock had a complex tectonic history; probable Cambrian – Late Proterozoic age (505 – 900 Ma).
Breccia Rockbridge County 27. Breccia Rockbridge County Donated By: Rockbridge Stone Products, Inc., Glasgow Plant Light brown fragments of quartzite (Antietam Formation) welded together by a dark brown matrix of manganese – iron oxide. Breccia formed by faulting during, or near, the end of the Permian (245 – 286 Ma).
Iron Ore Alleghany County 28. Iron Ore Alleghany County Donated By: Gerald P. Wilkes Result of secondary mineralization caused by groundwater percolating downward through ironbearing shale formations and precipitating iron oxides upon reaching a lower sandstone formation (Oriskany Formation). From the Jordan Mines. Undetermined age; probably within the last 200 million years.
Zinc Ore Rockingham County 28A. Zinc Ore Rockingham County Donated By: C. L. Custer Result of secondary mineralization by fluids moving through a collapse breccia of limestone and dolostone, Beekmantown Formation, Ordovician (440 – 505 Ma). . Zinc bearing sphalerite is the primary ore mineral, with scattered pyrite. From the Bowers-Campbell Mine. Undetermined age; probably pre-Permian (286 Ma).
Mineralized Limestone Highland County 29. Mineralized Limestone Highland County Donated By: Miracle Ridge Limestone Zone of mostly calcite mineralization within the Tonoloway Formation, Silurian (410 – 440 Ma). Possibly related to igneous injections and hot fluid movement during the Tertiary Period (1.8 – 65 Ma).
Open-folded, Biotite-Hornblende- Feldspar Gneiss Hanover County 30. Open-folded, Biotite-Hornblende- Feldspar Gneiss Hanover County Donated By: U. S. Silica Corporation, Montpelier Quarry Open-folded, biotite, hornblende, quartz, and feldspar gneiss with scattered anorthite and garnets. Interpreted as sediments that were metamorphosed during Grenville-age regional metamorphism (approx. 900 – 1200 Ma). Montpelier Metanorthosite, Middle Proterozoic (900 – 1600 Ma).
Conglomerate Loudoun County 31. Conglomerate Loudoun County Donated By: Town of Leesburg, Ida Lee Park Composed of rounded to subangular pebbles, and cobbles of mixed lithologies including limestone, dolostone, quartzite, gneiss, schist, and greenstone in a fine- to medium-grained maroon, silty sandstone matrix. Approximately 240 million years ago North America and South America separated from Europe and Africa. This breakup resulted in the creation of several down-dropped rift basins that filled with sediment. This conglomerate formed from debris falling into the basin along the western margin of the Culpeper Basin. Leesburg Member of the Balls Bluff Siltstone, Triassic (208 – 245 Ma).
Rhythmite Smyth County 32. Rhythmite Smyth County Donated By: James Lovett Maroon and greenish sandstone / siltstone exhibiting cyclic sedimentation. Konnarock Formation, Late Proterozoic (544 – 900 Ma).
Mineralized Metabasalt (Greenstone) Albemarle County 33. Mineralized Metabasalt (Greenstone) Albemarle County Donated By: Luck Stone Corporation, Charlottesville Plant Grayish-green, to dark-yellowish-green, finegrained, schistose metabasalt. Composed of chlorite, actinolite, albite, epidote, quartz, and magnetite. Fractured zone is filled with pink plagioclase, white quartz, and pistachio-green epidote. Result of eruption of flood basalts. Catoctin Formation, Late Proterozoic (544 – 900 Ma).
Granite Gneiss with Pink Pegmatite Veins Chesterfield County 34. Granite Gneiss with Pink Pegmatite Veins Chesterfield County Donated By: Vulcan Materials Company, Dale Quarry Light-gray, equigranular, medium-grained, foliated granite gneiss. Multiple intrusive phases common. Composed of quartz, sodic and potassium feldspars, biotite, and hornblende. This granite gneiss, commonly called the Petersburg Granite, has been radiometrically dated at 330 Ma; Mississippian (325 – 360 Ma).
Quartzite with Skolithus Tubes Augusta County 35. Quartzite with Skolithus Tubes Augusta County Donated By: Boxley Aggregates, Stuarts Draft Plant White quartzite with vertical tubes (worm burrows?) called Skolithus linearis. Antietam Formation of the Chilhowee Group, Cambrian (505 – 544 Ma). NO. 2/3 VIRGINIA MINERALS 19
Hydrothermally Altered Ultramafic Rock Grayson County 36. Hydrothermally Altered Ultramafic Rock Grayson County Donated By: Cardinal Stone Company, Grayson Quarry Greenish-black, fine- to medium- grained, massive, metaperidotite. Composed of serpentine, amphibole, chlorite, and magnetite. The upper surface of this sample displays “slickensides”. Slickensides form between two rock units when they are faulted (ground) against each other. These slickensides are composed of chlorite and epidote. Ultramafic rocks form deep in the earth and are brought to the surface by tectonism. Alligator Back/Ashe Formation of the Lynchburg Group, Cambrian – Late Proterozoic (505 – 900 Ma).
Pebble Conglomerate Russell County 37. Pebble Conglomerate Russell County Donated By: Town of Saint Paul Sandstone conglomerate composed of rounded, “jelly-bean” quartz pebbles. Lee Formation, Pennsylvanian (286 – 325 Ma)
Blue Kyanite Prince Edward County 38. Blue Kyanite Prince Edward County Donated By: Kyanite Mining Corporation, Baker Mountain Plant Matted, intergrown mass of blue kyanite crystals. Formed by metamorphism of aluminum-rich sediments; kyanite has the characteristic of being resistant to high temperatures. It is used in high temperature resistant products such as brake linings, spark plugs, molds for steel castings, and tiles on the space shuttle. Probable Ordovician age (440 – 505 Ma).
Garnet-Hornblende-Feldspar Gneiss Hanover County 39. Garnet-Hornblende-Feldspar Gneiss Hanover County Donated By: U. S. Silica Corporation, Montpelier Quarry Gneiss composed of hornblende, biotite, and feldspar with large garnets and pods of anorthosite. Interpreted as sedimentary rocks that were metamorphosed during Grenville-age regional metamorphism (approx. 900 – 1200 Ma). Montpelier Metanorthosite, Middle Proterozoic (900 – 1600 Ma).
Bituminous Coal Wise County 40. Bituminous Coal Wise County Donated By: Coastal Coal Company LLC Combustible organic rock with a high percentage of carbon. Coal is Virginia’s most valuable mineral resource. This specimen was treated to prevent deterioration. Wise Formation, Pennsylvanian (286 – 325 Ma).
Shelly Calcareous Sandstone New Kent County 41. Shelly Calcareous Sandstone New Kent County Donated By: Mr. & Mrs. George, Jr. and Becky Philbates Philbates Auto Wrecking, Inc. Brownish-yellow to gray, fine- to coarse-grained, calcareous sandstone with abundant shell material mixed with clay. Yorktown Formation, Pliocene (1.8 to 5 Ma).
White Kyanite Buckingham County 42. White Kyanite Buckingham County Donated By: Kyanite Mining Corporation, Willis Mountain Plant Matted, intergrown and layered white kyanite crystals in a quartz matrix. Kyanite has the characteristic of being resistant to high temperatures. Kyanite is used in many high temperature resistant products such as, brake linings, steel castings, spark plugs, and tiles on the space shuttle. Probable Ordovician age (440 – 505 Ma).
Garnetiferous Biotite Gneiss Henry County 43. Garnetiferous Biotite Gneiss Henry County Donated By: Boxley Aggregates, Fieldale Plant Sample is light- to medium-gray, mediumgrained, polydeformed, polymetamorphosed, porphyroblastic, irregularly-layered, garnetiferous biotite gneiss. Interpreted as a highly metamorphosed sedimentary rock showing incipient melt zones. Fork Mountain Formation, Cambrian – Late Proterozoic (505 – 900 Ma).
Granite Gneiss Grayson County 44. Granite Gneiss Grayson County Donated By: Lyall Stone, Inc. Equigranular, medium-grained, lineated quartz, feldspar, biotite, monzonite gneiss, with scattered blebs of blue quartz and chalcopyrite. Radiometrically dated at 1050 – 1080 Ma. Cranberry Gneiss (?) of the Elk Park Plutonic Group, Middle Proterozoic (900 – 1600 Ma).
Unakite Rockbridge County 45. Unakite Rockbridge County Donated By: Bob Kopecko Coarse-grained, metamorphic rock of a granite composition. Reddish-brown microcline feldspar, pistachio green epidote, white plagioclase feldspar, and light gray quartz. Is valued as a semi-precious stone for making jewelry and was once proposed as the State rock of Virginia. Probable formation during Grenville time (900 – 1200 Ma). Found in Blue Ridge basement complex, Middle Proterozoic (900 – 1600 Ma).

Fossil Tree Trunk Wise County 46. Fossil Tree Trunk Wise County Donated By: Coastal Coal Company, LLC Sand impregnated, fossilized, lycopod (scale tree) trunk (Sigillaria/Lepidodendron) from ancient swamp-land sedimentation comprising coal measures. Wise Formation, Pennsylvanian (286 – 325 Ma).
Garnet-Biotite-Hornblende Gneiss Greene County 47. Garnet-Biotite-Hornblende Gneiss Greene County Donated By: Luck Stone Corporation, Greene Plant Light and dark colored, medium- to coarsegrained, biotite-rich, quartzo-feldspathic gneiss. It is composed of biotite, quartz, feldspar, garnet, hornblende, and muscovite. A Blue Ridge basement rock with a Grenville-age metamorphic overprint (900 – 1200 Ma); original igneous pluton Middle Proterozoic (900 – 1600 Ma).
Sandstone with Turritella Fossils King George County 48. Sandstone with Turritella Fossils King George County Donated By: Village of Fairview Beach Glauconitic quartz sandstone with large, highspired gastropods, Turritella mortoni. Aquia Formation, Paleocene (54 to 65 Ma).
Collapse Breccia Augusta County 49. Collapse Breccia Augusta County Donated By: Plecker Construction Company Collapse breccia formed in a splay of the Staunton Fault zone. It has been cemented with calcite and dolomite crystals. Conococheague Formation, Cambrian (505 – 544 Ma).
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