File:Corundum (Pennsylvania, USA) 5.jpg
![File:Corundum (Pennsylvania, USA) 5.jpg](https://upload.wikimedia.org/wikipedia/commons/thumb/4/44/Corundum_%28Pennsylvania%2C_USA%29_5.jpg/654px-Corundum_%28Pennsylvania%2C_USA%29_5.jpg?20230919172515)
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[edit]DescriptionCorundum (Pennsylvania, USA) 5.jpg |
English: (cut surface; ~7.5 centimeters across at its widest)
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 over 5900 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 oxide minerals all contain one or more oxide anions (O-2). The oxide minerals include species that are hydroxy-oxides. The hydroxide minerals (those with one or more OH-) are usually considered together with the oxides. Many sulfide minerals are not stable in Earth-surface conditions. In the presence of oxygen and moisture, sulfide minerals tend to tarnish or alter to oxides and hydroxy-oxides. All except the most inert elements (such as the platinum-group elements and gold and noble gases) readily form oxides. Gold oxide forms only under special conditions. Corundum is aluminum oxide - Al2O3. At H≡9, it is the hardest common mineral, apart from diamond. Corundum forms hexagonal crystals, which is evident even in many river-worn specimens. The hexagonal columns of corundum typically have well-developed flat tops & bottoms. These flat ends are not cleavage planes - corundum has no cleavage. The cleavage-looking flat tops & bottoms of corundum are called partings (pseudocleavage). Additional breakages will not be along planar surfaces. The color of corundum is variable - it can be any color, including plaid patterns. If transparent and relatively fracture-free & inclusion-free, corundum is said to be of gem-quality, and the color determines the name of the gem. deep red = ruby blue = sapphire pale red = sapphire pale green = sapphire purple = sapphire yellow = sapphire The corundum crystal seen here is quite eroded, but its hexagonal crystal shape is still obvious. This specimen is large and dense - it weighs 3 pounds, 1 ounce. Locality: unrecorded / undisclosed site in Pennsylvania, USA Photo gallery of corundum: www.mindat.org/gallery.php?min=1136 |
Date | |
Source | https://www.flickr.com/photos/47445767@N05/53196917337/ |
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@N05/53196917337. It was reviewed on 19 September 2023 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0. |
19 September 2023
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current | 17:25, 19 September 2023 | ![]() | 2,828 × 2,594 (4.61 MB) | Ser Amantio di Nicolao (talk | contribs) | Uploaded a work by James St. John from https://www.flickr.com/photos/47445767@N05/53196917337/ with UploadWizard |
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Camera manufacturer | Canon |
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Camera model | Canon PowerShot D10 |
Exposure time | 1/40 sec (0.025) |
F-number | f/4 |
ISO speed rating | 320 |
Date and time of data generation | 17:03, 28 January 2013 |
Lens focal length | 11.614 mm |
Width | 4,000 px |
Height | 3,000 px |
Bits per component |
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Pixel composition | RGB |
Orientation | Normal |
Number of components | 3 |
Horizontal resolution | 180 dpi |
Vertical resolution | 180 dpi |
Software used | Adobe Photoshop Elements 18.0 (Macintosh) |
File change date and time | 17:49, 18 September 2023 |
Y and C positioning | Co-sited |
Exif version | 2.21 |
Date and time of digitizing | 17:03, 28 January 2013 |
Meaning of each component |
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Image compression mode | 2 |
APEX shutter speed | 5.3125 |
APEX aperture | 4 |
APEX exposure bias | −0.33333333333333 |
Maximum land aperture | 4 APEX (f/4) |
Metering mode | Pattern |
Flash | Flash did not fire, compulsory flash suppression |
Supported Flashpix version | 1 |
Color space | sRGB |
Focal plane X resolution | 16,460.905349794 |
Focal plane Y resolution | 16,483.516483516 |
Focal plane resolution unit | inches |
Sensing method | One-chip color area sensor |
File source | Digital still camera |
Custom image processing | Normal process |
Exposure mode | Manual exposure |
White balance | Auto white balance |
Digital zoom ratio | 1 |
Scene capture type | Standard |
Lens used | 6.2-18.6 mm |
Date metadata was last modified | 13:49, 18 September 2023 |
Unique ID of original document | 336BEF316D5DFEBC171094CBA84449F3 |