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Quartz : SiO2

How to use the mindat.org media viewer

Click/touch this help panel to close it.

Welcome to the mindat.org media viewer. Here is a quick guide to some of the options available to you. Different controls are available depending on the type of media being shown (photo, video, animation, 3d image)

Controls - all media types

Zoom in and out of media using your mousewheel or with a two-finger 'resize' action on a touch device.

Use the mouse or your finger to drag the image or the view area of the image around the screen.

< and > at the left and right hand side of the screen move forwards and backwards for the other images associated with the media you selected. Usually this is used for previous/next photo in a gallery, in an article or in search results. Keyboard shortcuts: use shift + the left and right arrow keys.

< and > in the bottom center are used for switching between the photos of the same specimen. Keyboard shortcuts: use the left and right arrow keys.

>  in the bottom center, raises the information box giving details and further options for the media,  <  at the top of this box then hides it. Keyboard shortcuts: use the up and down arrow keys.

? opens this help window. Keyboard shortcuts: use the H key or the ? key.

Other keyboard shortcuts:

1Fit image to screen
2Fill screen with image
5Display at full resolution
<Make background darker
>Make background lighter
spaceHide/dim titles and buttons

Scalebar

If the field of view (FOV) is specified for the photo, the scalebar appears in the left bottom corner of the viewer. The scalebar is draggable and resizeable. Drag the right edge to resize it. Double click will reset the scalebar to it's default size and position. If the scalebar is in default position, double click will make it circular.

Controls - Video

Video files have a standard set of video controls: - Reset to start, - Skip back, - Play, - Pause, - Skip forwards. Keyboard shortcuts: You can stop/start video play with the P key.

Controls - Animation (Spin Rotation)

Animation (usually 360 degree spin rotations) have their own controls: - enable spin mode. Note that while images are loading this option will not be available but will be automatically activated when the animation has loaded. Once active you can spin the image/change the animation by moving your mouse or finger on the image left/right or by pressing the [ or ] keys.

The button switches to move mode so that you can use your mouse/fingers to move the image around the screen as with other media types.

The button, or the P key will start playing the animation directly, you can interrupt this by using the mouse or finger on the image to regain manual movement control.

Controls - 3D Stereoscopic images

If a stereoscopic 3D image is opened in the viewer, the 3D button appears in the bottom right corner giving access to "3D settings" menu. The 3D images can be viewed in several ways:
- without any special equipment using cross-eyed or parallel-eyed method
- with stereoscope
- with anaglyph glasses.
- on a suitable 3D TV or monitor (passive 3D system)

For details about 3D refer to: Mindat manuals: Mindat Media Viewer: 3D

To enable/disable 3D stereo display of a compatible stereo pair image press the 3 key. If the left/right images are reversed on your display (this often happens in full-screen mode) press the 4 key to reverse them.

Controls - photo comparison mode

If a photo with activated comparison mode is opened in the viewer, the button appears in the bottom right corner giving access to "Comparison mode settings" menu.

Several layouts are supported: slider and side by-side comparison with up to 6 photos shown synchronously on the screen. On each of the compared photos a view selector is placed, e.g.:  Longwave UV ▼. It shows the name of currently selected view and allows to select a view for each placeholder.

Summary of all keyboard shortcuts

1Fit image to screen
2Fill screen with image
3Switch to 3D display of stereo pair
4Switch left/right images in 3D mode
5Display at full resolution
<, >Make background darker/lighter
H or ?Show/hide this help page
PPlay/Pause Video or Animation
[, ]Backwards/forwards one frame (Animation only)
spaceHide/dim titles and buttons
up arrowShow information box
down arrowHide information box
left arrowPrevious child photo
right arrowNext child photo
shift + left arrowPrevious image on the page
shift + right arrowNext image on the page


Copyright © John A. Jaszczak
 
 
 
 
minID: Y59-22J

Quartz : SiO2

Copyright © John A. Jaszczak  - This image is copyrighted. Unauthorized reproduction prohibited.
Largest Crystal Size: 0.75 mm

Well-formed 0.75 mm negative crystal in a 1.1-cm Herkimer-diamond-like quartz crystal. Although this crystal does not show two phases of fluid in the negative crystal, some negative crystals in similar crystals show movable gas bubbles. This crystal has only minor associated graphite, but similar crystals also have lustrous well-formed graphite crystals as inclusions.

This Photo was Mindat.org Photo of the Day - 8th Aug 2016

This photo has been shown 1362 times
Photo added:22nd Dec 2015
Dimensions:4268x2845px (12.14 megapixels)
Camera:CANON EOS 600D / Rebel T3i / Kiss X5

Data Identifiers

Mindat Photo ID:723045 📋 (quote this with any query about this photo)
Long-form Identifier:mindat:1:4:723045:2 📋
GUID:f0664946-2559-460f-84ef-494fbe1f10f2 📋
Specimen MinIDY59-22J (note: this is not unique to this photo, it is unique to the specimen)

Discuss this Photo

PhotosQuartz - Merelani Hills, Lelatema Mts, Simanjiro District, Manyara Region, Tanzania

8th Aug 2016 12:09 UTCRonnie Van Dommelen 🌟 Manager

How would something like this form? Thanks.

8th Aug 2016 12:32 UTCWayne Corwin

Negitive crystals (tu)

8th Aug 2016 12:39 UTCRonnie Van Dommelen 🌟 Manager

Wayne,

Yes I saw the description. I can even imagine if it was a negative crystal of another mineral how it might form but I cannot for the same mineral. As I understand it, atoms fall into place preferentially in low energy locations and thus we get characteristic crystal shapes. So why would the atoms that were clearly all around the void not want to adhere to the crystal?

8th Aug 2016 16:07 UTCJohn A. Jaszczak Expert

Ronnie,

These negative crystals are actually voids, not solid crystals that are misoriented in a larger host. The crystal shape of the negative crystal here

is aligned with the host crystal. It is not obvious in this specimen, but these inclusions are filled with fluid, and in some crystals of quartz from Merelani,

also have movable gas bubbles. I have not yet done Raman spectroscopy to identify the fluid in these, but extensive fluid inclusion work

on inclusions in quartz and tanzanite is in the literature.

The shape of the negative crystal is a formed by surfaces between the void and the host crystal and should be fairly similar to the external shape

of the host crystal (inverted) unless the host crystal underwent other episodes of growth/dissolution that the negative crystal did not experience. I'm not clear about what you mean about the atoms around the void not wanting to adhere to the crystal. Perhaps you can explain more?

Sincerely

John

8th Aug 2016 16:22 UTCRob Woodside 🌟 Manager

If the surface tension between the crystal and fluid is very high then it costs a lot of energy to make surface area between them. The smallest area enclosing a volume is a sphere, so with large surface energy or tension the inclusions are spheres. As the surface energy decreases rounded linear features start to appear and if the surface energy is very small then we can get sharp edges and corners on the negative xls. For this one it looks like the surface energy vanished!

8th Aug 2016 21:50 UTCDana Morong

Rob Woodside is correct. If one wants to see some diagrams of the process, try to get and read a copy of "Ancient Fluids in Crystals" by Edwin Roedder, in the October 1962 issue of Scientific American magazine, volume 207, n.4, pages 38-47. The idea is that a fracture healed, leading to little areas of fluid, and due to movement of silica, the negative areas eventually got 'faceted' to the lowest energy, the least surface area.

Sometimes I have seen very tiny negative crystals along a plane within a larger quartz crystal (under the microscope).
 
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