File:Amethyst (Homestake Mine, Lead, Black Hills, South Dakota, USA) (33022454586).jpg
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[edit]DescriptionAmethyst (Homestake Mine, Lead, Black Hills, South Dakota, USA) (33022454586).jpg |
Amethyst from South Dakota, USA. (SDSM 1726, South Dakota School of Mines Museum of Geology, Rapid City, South Dakota, USA) A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are about 5400 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates. The silicates are the most abundant and chemically complex group of minerals. All silicates have silica as the basis for their chemistry. "Silica" refers to SiO2 chemistry. The fundamental molecular unit of silica is one small silicon atom surrounded by four large oxygen atoms in the shape of a triangular pyramid - this is the silica tetrahedron - SiO4. Each oxygen atom is shared by two silicon atoms, so only half of the four oxygens "belong" to each silicon. The resulting formula for silica is thus SiO2, not SiO4. The simplest & most abundant silicate mineral in the Earth's crust is quartz (SiO2). All other silicates have silica + impurities. Many silicates have a significant percentage of aluminum (the aluminosilicates). Quartz (silicon dioxide/silica - SiO2) is the most common mineral in the Earth's crust. It is composed of the two most abundant elements in the crust - oxygen and silicon. It has a glassy, nonmetallic luster, is commonly clearish to whitish to grayish in color, has a white streak, is quite hard (H≡7), forms hexagonal crystals, has no cleavage, and has conchoidal fracture. Quartz can be any color: clear, white, gray, black, brown, pink, red, purple, blue, green, orange, etc. Purple quartz is called amethyst. The coloring agent for amethyst is not agreed upon. Some workers say that it is due to Fe+4 impurity, some say the impurity is Fe+3, and others say it is Mn. Locality: Homestake Mine, town of Lead, northern Black Hills, western South Dakota, USA Photo gallery of quartz and amethyst <a href="http://www.mindat.org/gallery.php?min=3337" rel="nofollow">www.mindat.org/gallery.php?min=3337</a> and <a href="https://www.mindat.org/gallery.php?min=198" rel="nofollow">www.mindat.org/gallery.php?min=198</a> |
Date | |
Source | Amethyst (Homestake Mine, Lead, Black Hills, South Dakota, USA) |
Author | James St. John |
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This image was originally posted to Flickr by James St. John at https://flickr.com/photos/47445767@N05/33022454586 (archive). It was reviewed on 5 December 2019 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0. |
5 December 2019
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Date/Time | Thumbnail | Dimensions | User | Comment | |
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current | 02:04, 5 December 2019 | 1,791 × 1,449 (2.66 MB) | Ser Amantio di Nicolao (talk | contribs) | Transferred from Flickr via #flickr2commons |
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Metadata
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Camera manufacturer | EASTMAN KODAK COMPANY |
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Camera model | KODAK EASYSHARE Z1012 IS Digital Camera |
Exposure time | 1/50 sec (0.02) |
F-number | f/3.2 |
ISO speed rating | 64 |
Date and time of data generation | 11:53, 19 August 2010 |
Lens focal length | 13.2 mm |
Orientation | Normal |
Horizontal resolution | 480 dpi |
Vertical resolution | 480 dpi |
Software used | Adobe Photoshop CS2 Macintosh |
File change date and time | 23:14, 22 February 2017 |
Y and C positioning | Centered |
Exposure Program | Normal program |
Exif version | 2.21 |
Date and time of digitizing | 11:53, 19 August 2010 |
Meaning of each component |
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APEX shutter speed | 5.6666666666667 |
APEX aperture | 3.4 |
APEX brightness | 0 |
APEX exposure bias | 0 |
Maximum land aperture | 3.4 APEX (f/3.25) |
Metering mode | Pattern |
Light source | Unknown |
Flash | Flash did not fire, auto mode |
DateTimeOriginal subseconds | 30 |
Supported Flashpix version | 1 |
Color space | sRGB |
Exposure index | 64 |
Sensing method | One-chip color area sensor |
File source | Digital still camera |
Scene type | A directly photographed image |
Custom image processing | Custom process |
Exposure mode | Auto exposure |
White balance | Auto white balance |
Digital zoom ratio | 0 |
Focal length in 35 mm film | 65 mm |
Scene capture type | Standard |
Scene control | None |
Contrast | Normal |
Saturation | Normal |
Sharpness | Normal |
Subject distance range | Unknown |
Supported Flashpix version | 1 |
Image width | 1,791 px |
Image height | 1,449 px |
Date metadata was last modified | 18:14, 22 February 2017 |