Assembly of TotBlocks
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| Anzahl der Teile | 13 | |
| Autor | 0000-0002-3282-4691 (ORCID) 0000-0002-3023-9667 (ORCID) | |
| Lizenz | CC-Namensnennung 4.0 International: Sie dürfen das Werk bzw. den Inhalt zu jedem legalen Zweck nutzen, verändern und in unveränderter oder veränderter Form vervielfältigen, verbreiten und öffentlich zugänglich machen, sofern Sie den Namen des Autors/Rechteinhabers in der von ihm festgelegten Weise nennen. | |
| Identifikatoren | 10.5446/57471 (DOI) | |
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Inhaltliche Metadaten
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01:47
Computeranimation
02:59
Computeranimation
03:23
Computeranimation
05:10
Computeranimation
05:29
Karte (geographisch)
05:51
Karte (geographisch)
08:33
Karte (geographisch)
11:11
Karte (geographisch)Computeranimation
Transkript: Englisch(automatisch erzeugt)
00:00
Minerals are the building blocks of the earth, but did you know that minerals themselves are commonly made of shared building blocks? We can visualize the crystal structures of these minerals using a series of 3D printed building blocks, called top blocks. In this video, we'll explore the building blocks that make up these common minerals, how we can make chains from them, and how we can link these chains together.
00:23
Modular rock forming minerals consist of two types of modules, T-modules and O-modules. The T-modules represent chains of corner-sharing silicon tetrahedra. Within each tetrahedron is a single silicon atom bonded to four oxygen atoms, forming a tetrahedron.
00:40
The O-modules represent ribbons of edge-sharing metal-oxygen octahedra. Within each octahedron is a metal ion that is bonded to six oxygen atoms. These metal ions can include magnesium, iron, and aluminum. The T and O-modules are joined by shared oxygen atoms, forming the backbone of these mineral structures.
01:02
Things start to get visually complicated when we start to arrange multiple T and O-modules. One way to solve this problem is to show the atomic sites as polyhedra by joining the oxygen atoms that surround the cations. This simplifies the structure and emphasizes the common building blocks between different minerals.
01:21
The orientations of these modules relative to one another are important because the modules are not exactly symmetrical, which leads to variations in the mineral structures. The way that we'll be thinking about orientations in this series is that positive orientations will be when the module is pointing up, and negative orientations are when the module is pointing down, when the width-wise pegs are facing rightward.
01:43
Both the T and O-modules can be either positive or negative. Here is a T-plus module. Note that the tops of the tetrahedra are pointing upwards. In contrast, here is a T-minus module where the tops of the tetrahedra are pointing downwards. It's a similar situation for the O-modules.
02:01
These green modules are called the O-plus modules because when the pegs are rightward, the octahedra point upwards. On the other hand, these yellow modules are called O-minus modules because when the pegs are rightward, the octahedra are pointing downwards. Keep in mind that if we take a TOT module and flip it around, still keeping the width-wise
02:21
pegs oriented rightward, that the T-module that was on top is now on the bottom, and vice versa. However, it has changed from a T-plus module to a T-minus module. This shows that the T-modules are reversible to some degree, but the notation that we use is not specific to the type of module, but rather the orientation of the module. On the other hand, if we try to rotate the O-plus module the same way, it stays as an
02:45
O-plus module, it doesn't change to an O-minus module. In order to make an O-minus module, we would have to rotate it a different way, but then the width-wise pegs would end up on the wrong side, so these modules are distinct. We'll need a couple of additional pieces to make some of the modular rock forming minerals.
03:05
For the layered minerals, specifically the 2 to 1 phyllosilicates, and the brucite, kaolinite serpentine, and chlorite groups, extra octahedra are needed to fill missing M-sites within the O-modules. How do we end up with M-sites missing in our building blocks?
03:23
Well, the modules themselves are subdivisions of a theoretically infinite sheet, and we're making cuts between continuous chains of silicon tetrahedra. However, this infinite sheet doesn't have a 1 to 1 match-up between the pairs of silicon tetrahedra and the octahedral M-sites.
03:42
For example, a single chain width TOT module is made up of 4 tetrahedra and 2 octahedra. Now here's a double chain width module. We might expect to see 4 octahedra for 8 tetrahedra, but instead we actually have 5 octahedra.
04:01
We've got one extra. The octahedra in position 3 end up shared between our single chains and serves to keep the O-module continuous. We can account for these extra octahedra by using custom printed pieces. Using these extra octahedron pieces, single chain width modules can be joined together
04:23
using the phyllosilicate type linkage to make double chain width modules, and so on. There are two different types of extra octahedra, one has clips and one doesn't, but there's no theoretical difference between them. We found in prototyping that the octahedra found at the outer edges need clips to stay
04:44
attached to the modules, whereas the octahedra inserted within the modules don't need these clips. The last pieces featured in top blocks are pegs of various lengths, which are used to vertically stack the individual sheets in the layered minerals.
05:00
These pegs don't denote specific chemical bonds between the layers, they just help us to get a better visual understanding of the sheeted nature of the structures. Now that we've seen all of the building blocks, let's start putting them together. The first thing we'll look at is making chains from these tetrahedra and octahedra. This is a side by side comparison of the two different types of T and O modules from
05:21
top view for single chain width modules. Here's the same comparison, but for double chain width modules. Finally, here are the modules for the triple chain width series. These are the TOT modules, with O plus modules as the O modules, and there's single
05:41
chain width, double chain width, and triple chain width modules. This is a single chain width T O plus T module. Now we'll take it apart. When constructing the TOT modules, be sure that the pegs are facing the same direction, in this case right, and also that the two T modules are different, so they're mirrors
06:04
of each other, as opposed to being the same modules. It's important to be consistent with which T module is on top and which is on the bottom, because that will be important with joining the modules lengthwise, if desired. And so, starting with the T plus module, the O plus module is stacked on top, and
06:32
then the T minus module falls on it, like so.
06:41
This is a double chain width T O plus T module. Now we'll take it apart, and you can use a straight edge to take apart the modules.
07:11
The same principle applies for the double chain width modules, so again the pegs go in the same direction, and two different types of modules, the two different T modules.
07:25
And so we have the T plus, which goes on the bottom of the O module, and then the T minus goes on top, like so.
07:48
This is the triple chain width T O plus T module. Now we'll take it apart, and you can use a straight edge to take apart the modules.
08:23
And again, pegs on the same side, make sure these are different modules, and so we stack again.
08:51
All of the building blocks that we've looked at so far use O plus modules. The same arrangements can be made with O minus modules. This is a single chain width T O minus T module.
09:02
Now we'll take it apart. So again, when we're constructing these modules, we want the pegs to be all pointing in the same direction, and we want to make sure that they're two different T modules. So you can see in this case that they're mirrors.
09:22
And so this module goes on the bottom, then the O stacks on top, and then the T. And again, make sure that all of the pegs are pointing in the same direction.
09:42
This is a double chain width T O minus T module. Now we'll take it apart. And again, make sure the pegs are all pointing in the same direction, and that there are two different T modules.
10:03
And so the T goes on the bottom, then the O module goes like this. And then finally, the top T module goes up here.
10:21
This is a triple chain width T O minus T module. Now we'll take it apart.
10:49
The pegs are all pointing in the same direction, and there are two different T modules. So this one's going to be the base.
11:13
Now we've seen how to construct the different T O T modules. In the next section, we'll look at how the T O T modules can be connected with Y's.
11:23
There are three different ways to connect the T O T modules, and this will be demonstrated using single chain width modules. The first way to connect the T O T modules is to connect them horizontally such that the T minus connects with the T minus, the O connects with the O, and the T plus connects with the T.
11:46
And so this produces no vertical offset, and is known as the phyllosilicate type linkage. Minerals that have this linkage include the biotite series, muscovite, pyroflite, and talc.
12:01
The second type of linkage involves connecting the T minus to the bottom of the O, and also the top of the O to the T plus of the second module, like so. This produces a net vertical offset of two thirds of the T O T module,
12:21
and is known as the pyroflite type linkage. Minerals that have this linkage include the pyroxenes and amphiboles. The third linkage consists of T minus T plus linkages. So in this case, the T minus connects with the T plus.
12:40
This produces an offset of one T O T module, and this is known as the palisepial type linkage. Minerals that have this linkage include palygorska and sepiolite. To summarize, there are three types of linkages. There's the phyllosilicate type linkage, which has no vertical offset.
13:03
There is the pyrobl type linkage, which has an offset of two thirds of the T O T module. And finally, there is the palisepial type linkage, which has an offset of one T O T module. The three types of linkages define the three broad groups of minerals that consist of T and O modules.
13:21
First, the layered minerals. Second, the pyrobl series. And third, the palisepial series. Each of these linkages can be made with single chain width, double chain width, and triple chain width modules. Equipped with these different sizes of chains and the different ways we can connect them, we can build a multitude of minerals that can come in many shapes and sizes.
13:44
We will explore these mineral structures in other videos.