Talk:List of rock types

what is the use of this list, should this not be part of a category?

A category is not a list - lists have advantages: red links can be included as well as variety names that link to the major rock description. Of course lists aren't automated, but, hey that's what we get paid for :-) And once a category gets all settled someone comes along with a grand bold idea - and presto everything's changed, with no discussion at all. Vsmith 00:17, 7 September 2005 (UTC)

Add some science

I think that the list of rocks should include only those rocks which are recognised within the scientific literature; pseudo-rocks such as "rhomb porphyry" which are actually textures (eg; concretion) should be removed. Rocks should be restricted to those formally recognised by the IUGS or other stratigraphic or nomenclature committee otherise soon there will be an explosion of terms such as "fiamme-bearing porphyry" and so on. Rolinator 05:05, 20 December 2005 (UTC)

I've removed some rocks such as minette which are basicaly defunct terms for types of lamprophyre. [Theralite]] gets a pass for now because I haven't got the heart to rewrite/create a nepheline gabbro page; adakite is up for debate as it is a geochemical class of rocks (basically, a basalt with an implied tectonic signature in its trace elements). Tezontle is gone, as it is a trade name for a rock borolanite is not a rock type it's another defunct archaic term.

However, this raises some questions. Shoshonite, adakite, etc, really throw the door open on what is a list of rock types if it is inclusive or rocks classified on geochemical grounds? Is this right? I personally don't think so, because I'd be hard pressed to spot the difference between a shoshonite and an adakite in the field or under a microscope. So we need to think about how to link to another list of these types of "rocks", and where to list archaic or out-of-use names for rocks eg, borolanite, etc.

The prefered way would be to just link to the rock type which is now used, and leave a placeholder name in place. Alternatively, a link up top to a List of archaic rock names and List of scientific rock jargon?Rolinator (talk) 07:36, 28 March 2009 (UTC)

2 things. (1) Looking at this and the discussion in the section below, perhaps this could be split into two lists: an alphabetized (i.e., the current) one, with just about everything, and then another one that is scientifically defined (i.e., sandstone w/ bullet points below; limestone with bullet points below; intrusive and extrusive rocks with respect to composition). (2) Tezontle is the word that Mesoamerican archaeologists use for the volcanic rock that the Mesoamericans used as filler for their works of monumental architecture. If it linked to a trade name, the link should go, but as per my above catch-all alphabetized list idea, it should stay, though it shouldn't be in the classification-scheme list. Awickert (talk) 08:24, 28 March 2009 (UTC)

Tezontle and others are now living over on list of stones. Rolinator (talk) 09:47, 28 March 2009 (UTC)

Sounds good - sorry for missing your reply. And thanks for your work in getting the descriptions applied. If you want to work on a scientific classification in addition to the alphabetical, leave a message on my TP, and I'll join in and help. Awickert (talk) 02:21, 2 April 2009 (UTC)

Wackestone

Wackestone should not be included in this list of rocks, considering it is not a type of rock, but a type of limestone. If it were included, many other such examples would have to be included (e.g. boundstone, mudstone, packstone, grainstone) --Emergen 21:05, 20 March 2007 (UTC)

Since limestone is a rock, it is entirely appropriate for wackestone, as well as the others you name, to be on this list, IMO. Cheers Geologyguy 21:22, 20 March 2007 (UTC)

Yes, wackestone belongs - someone should do an article on it though.

I would like to see this simple alphabetical list re-organized into a simple rock classification scheme to convey more info. The current list really serves little purpose. Thoughts? Vsmith 22:49, 20 March 2007 (UTC)

Great idea. I'd be able to help with that, but not for the next 2 weeks. Cheers Geologyguy 23:50, 20 March 2007 (UTC)

I've been looking at how a simple classification scheme might work, but found that if you keep it simple you can only cover a small number of the rock types in one scheme; you would need at least four separate classifications to cover most of them and in some cases they don't fit into any (e.g. turbidite, the rock is mainly defined by its mechanism of deposition and can be muddy or sandy). It all seemed so simple when I started but it got so complex that I think, reluctantly, it's unworkable. Of course if someone can come up with a clever scheme that does the job, that would be great. An alternative would be to write a simple sentence on each rock type for each one in the list. e.g.

Amphibolite - A medium grade metamorphic rock of basaltic composition

Andesite - An intermediate fine-grained igneous rock

Anorthosite - A rare coarse-grained igneous rock composed mainly of calcium-rich plagioclase feldspar

Anthracite - A low-grade metamorphic rock derived from coal

Aplite - A fine-grained intrusive rock of granitic composition

Argillite - A general term for a mudstone/claystone

Arkose - A sandstone with a large component of feldspar clasts

Then at least people would get some info on how there particular rock type fits into the great scheme of things; any thoughts? Mikenorton 18:11, 29 September 2007 (UTC)

Suggested redirect to List of famous rocks

This is a list of common rock types, there is no cause to redirect it to an unrelated page.Mikenorton 20:56, 4 September 2007 (UTC)

Definetely not. I have replaced the proper redirect at the old List of rocks page to point to the renamed page and zapped the speedy delete tag there. A page with 50-100 incoming links is NOT a speedy candidate. I do however, support the renaming of this page - just leave the old redirect in place. Vsmith 23:37, 4 September 2007 (UTC)

Agreed, and thanks for doing that. Geologyguy 00:02, 5 September 2007 (UTC)

Revision

I revised the page as Mikenorton suggested, giving a description of the rock. I have moved Tezontle to the list of stone, along with unakite and some others. This way, they have their little day in the sun alongside their friends who are used for architecture and lapidiary pursuits, and our pure unsullied rocks can sit here in their ivory tower :P

I have also added a grab-bag category down the bottom, including the "non"-rocks and varieties of rocks which don't fit in, but which have some use to us. Eg; aphanite is a fair term is you don't have a lab with you in the field. This includes the archaic and vernacular terms, and can include all the oddities which defy easy classification (like all the peraklakine, alkaline and peraluminous rocks of Greenland, Finland, etc). When we can go and read the one or two papers on Ijolite, for instance, we can promote them to the full-blooded list above.

I have also left room for the varieties of rocks (eg; consider Basalt) which can be listed righ under the parent rock type, so that it is clear that a Hawaiite is a type of basalt.

I think this makes sense. Rolinator (talk) 09:47, 28 March 2009 (UTC)

OK, that's a great start, 18 months wasn't too long to wait for a response to my original suggestion:-). One idiosyncracy to sort out; Enderbite is a hypersthene-bearing tonalite but should such varieties from the opx-bearing charnockite series be listed under their more common cpx-bearing equivalents, i.e. in this case tonalite, in the 'Specific varieties' list, like mangerite, or in the main list, like charnockite and norite. I would go for first of these e.g.

Tonalite - a plagioclase-dominant granitoid

Enderbite - hypersthene-bearing tonalite

I'm not that fussed as long as we're consistent. Mikenorton (talk) 10:41, 28 March 2009 (UTC)

I guess we could (should?) consider it from a perspective of silica saturation - eg; norites are basically (no pun intended) Si-undersaturated gabbros. A fair amount of the Cpx/Opx divides are due to either temperature/pressure (depth) or composition (Si saturation), which is again related mostly to depth and degree of partial melting. I agree we need to be consistent...its time to hit Le maitre and et al. to see how to go forward: we can group the Si-undersaturated rocks together for a start (as suggested on the APF part of the QAPF diagram) or we can describe the si-undersaturated variants of si-saturated rocks. eg;

Rocks described according to the root Si-saturated rock which is most common ie; most familiar and a starting point to relate another rock to;

Gabbro - plutonic rock with plag and pyroxene

Essexite - Si undersaturated gabbro

Norite - Si undersaturated alkaline gabbro

Troctolite - basically an olivine gabbro

Ijolite - A rock separate from a gabbro, but still plutonic, Si-undersaturated

or, alternately, they would all be separated according to Si saturation;

Gabbro

Troctolite

Essexite

Norite

Ijolite

However, its still a list of rock types, not a QAPF or other genetically meaningful diagram. I think its relatively OK as it is, and we should shunt things around as they come to light. Rolinator (talk) 02:26, 2 April 2009 (UTC)

Icelandite

I moved Icelandite out of the "basalt" category because its composition is effectively Fe-rich, Al-poor andesitic, but unlike andesites, icelandite is formed in extensional environments. Icelandites could be included in a tholeiitic basalt suite, but that doesn't make them basalts (the suite could also include e.g. dacite or rhyolite). Perhaps including icelandite as a type of andesite on this list is a better option? Until then, I thought it would be better for it to stand alone. GeoWriter (talk) 13:46, 31 March 2009 (UTC)

Throw it in with andesite if you want, that maks sense. Rolinator (talk) 02:13, 2 April 2009 (UTC)