4meter

Looks like a piece of heavily rusted iron, or maybe some naturally baked clay. Would need to see what the inside core looks like for a definitive guess.

I think the others are correct, but it could also be the mineral Gypsum. Gypsum is very common in the dry desert SW. Hard to tell from the one picture. If Mica, then it will easily flake off in thin sheets; Gypsum will not.

It is a metamorphic rock, called Schist. It has been tumbled in a creek or river into the round cobble you now have.

Its a metamorphic rock (a Schist) with Garnet fragments. Its from Earth not space.

These are very nice samples of the famous Texas Ironstone. The outer shell is Hematite, and the inner core is a mixture of Goethite and Limonite. This was extensively mined back in the late 1800s, and early 1900s as a source of iron. There are many USGS publication from the 1920s on the mines and the source of the Ironstones.

Does not look like any mammoth tooth I have seen. I'm sure it is a piece of iron stained Sandstone with some grooves worn into it.

It is an Agate, but I see no evidence of fossil coral in the sample. It looks like it would be beautiful when sliced and polished. First give it a few days to a week soaking in a solution of Iron Out and water to remove the iron staining on the outside. Afterward, if there is any green stains or obvious lichens or other bios on the sample, soak it in a closed container with straight ammonia, outside, for a week to remove the bios. Always follow the manufactured directions, and use PPEs in a well ventilated area. Do not use cheap ammonia from the dollar store.

Based only on these photos, I would say photo #1 is a fine grain Granite; photo #2 is a Granite or Granodiorite, and photo # 3 is a Lamproite.

The photos resolution is not enough to show fine details. I will go out on a limb, and say that maybe the whole sample is made of broken fragments of former sea creatures "shells" cemented together. This is called "fossil hash". Sample may be a limestone (type of rock).

I don't see any fossils in the photos. Just a scuffed rock.

Gemology: the study of labeling an worthless rock(s) to sale it for a small fortune.

I like corundum; have not found any yet, but I would like to.

Ruby and Sapphire are the deep red, and deep blue colored varieties of corundum. Just in case anyone wanted to know.

I made a typo in my last post. It should read thus "Try the test again, and see if the Quartz "bits" into or gouges the test sample. If it does NOT," Sorry for any confusion.

Hello Sketch, Your 4'th and 5'th pics look like corundum (same mineral as Sapphire, just not blue color) a non-precious aluminum oxide mineral. Your last photo seems to shows Quart powder on the sample. Try the test again, and see if the Quartz "bits" into or gouges the test sample. If it does, the sample is harder than Quart. I would say that you have samples of Corundum.