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Albemarle Co., Virginia, USA

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Location is approximate, based on center of defined region.
 
Latitude & Longitude (WGS84): 38° 1' 22'' North , 78° 33' 23'' West
Latitude & Longitude (decimal): 38.02292,-78.55653
Neighbouring regions:


NOTE: The geographic coordinates presented are taken from the Charlottesville West topo map. The USGS GNIS database presents 24 sets of coordinates for this county.


Commodity List

This is a list of exploitable or exploited mineral commodities recorded from this region.


Mineral List

Mineral list contains entries from the region specified including sub-localities

Actinolite

Aegirine

Albite

var: Andesine

Almandine

Analcime

Anatase

Andradite

Anglesite

Ankerite

Anthophyllite

'Apatite'

Aragonite

'Asbestos'

Augite

Axinite-(Fe)

Azurite

Baryte

Beryl

var: Heliodor

'Biotite'

Bornite

Calcite

Cerussite

Chalcanthite

Chalcocite

Chalcopyrite

Chamosite

var: Thuringite

'Chlorite Group'

Churchite-(Y)

Clinozoisite

Cobaltite

Covellite

Cryptomelane

Cuprite

Dickite

Dolomite

var: Ferroan Dolomite

Epidote

Epsomite

Erythrite

'Fayalite-Forsterite Series'

'Florencite'

Fluorite

Galena

var: Argentiferous Galena

'Garnet'

Goethite

Gold

Graphite

Grossular

Grunerite

Gypsum

Halloysite-10Å

Halloysite-7Å

Hastingsite

Hematite

var: Martite

var: Specularite

'Hornblende'

Hydrozincite

Ilmenite

Jarosite

Kaolinite

'Limonite'

Lithiophorite

Magnesite

Magnetite

Malachite

Microcline

Mordenite

Muscovite

var: Illite

var: Sericite

Nontronite

'Olivine'

Opal

Orthoclase

'Psilomelane'

'Pumpellyite'

Pyrite

Pyromorphite

Pyrrhotite

Quartz

var: Agate

var: Amethyst

var: Aventurine

var: Blue Quartz

var: Chalcedony

var: Jasper

var: Milky Quartz

Rozenite

'Serpentine Subgroup'

Siderite

Siderotil

Smithsonite

'Soapstone'

Spessartine

Sphalerite

'Stilbite'

Sulphur

Talc

Tinticite

Titanite

Tremolite

Vermiculite

Wavellite

'Zeolite Group'

Zircon


78 valid minerals.

Rock Types Recorded

Note: this is a very new system on mindat.org and data is currently VERY limited. Please bear with us while we work towards adding this information!

Rock list contains entries from the region specified including sub-localities

Select Rock List Type

Alphabetical List Tree Diagram

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org

Mesoproterozoic
1000 - 1600 Ma



ID: 2982647
Porphyoblastic Biotite-Plagioclase Augen Gneiss

Age: Mesoproterozoic (1000 - 1600 Ma)

Description: Mesocratic, medium- to coarse-grained, biotite-rich quartzofeldspathic gneiss con tains prominent subhedral to euhedral monocrystalline feldspar augen. The ratio plagioclase: potassium feldspar may be as high as 10:1; color index ranges from 30 to 50. Apatite, epidote, muscovite, ilmenite, and titanite are ubiquitous accessories. Plagioclase contains abundant prismatic epidote and white mica; ilmenite is rimmed with masses of anhedral titanite; subhedral hornblende and subhedral to euhedral almandine-grossular garnet occur locally. In the vicinity of adjacent charnockite, anhedral actinolitic amphibole pseudomorphs after pyroxene or rims thoroughly uralitized relict pyroxene. Rock fabric is gradational from granofels to mylonite gneiss. Geophysical signature: negative magnetic signature relative to adjacent charnockite. In northern Virginia, this unit strongly resembles prophyroblastic granite gneiss (Ybp); however, the augen in Ybp are more commonly polycrystalline aggregates rather than single-crystal porphyroblasts. This unit is widespread in the central and southeastern Blue Ridge, encompassing a number of lithologically similar metaplutonic entities: the "biotitic facies"of the Roses Mill and Turkey Mountain ferrodiorites of Herz and Force (1987), the Archer Mountain quartz monzonite of Bartholomew and others (1981), biotite granofels and augen gneiss of Evans (1984, 1991), biotite augen gneiss of Conley (1989), and augen-bearing gneiss of Lukert and Halladay (1980), and Lukert and Nuckols (1976). Historically, most workers have interpreted these rocks as Grenville-age plutons in which the present-day biotite-rich mineral assemblage is a primary igneous assemblage that crystallized from a melt (for example, Bartholomew and others, 1981). Herz and Force (1987) and Evans (1991) presented evidence that these biotite gneisses were derived from charnockite plutons by retrograde hydration reactions. Pettingill and others (1984) reported ages of 1009±26 Ma (Rb-Sr whole-rock) and 1004±36 Ma (Sm-Nd whole-rock) for ferrodiorite to quartzmonzonite in the Roseland district. Where this unit has been mapped in the Upperville quadrangle (A.E. Nelson, unpublished data), U-Pb zircon data suggest a crystallization age of 1055±2 Ma (Aleinikoff and others, 1993).

Comments: Blue Ridge Basement Complex, Middle Proterozoic (Grenville-Age) Plutonic Rocks

Lithology: Major:{biotite gneiss}

Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. [133]

Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License


Localities in this Region


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References

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James L. Calver (1962) Geology and Mineral Resources of Albermarle County. Virginia Geological Survey; Bulletin 77.

Mineral and/or Locality  
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