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I acquired these two slices of something from a rockhound couple in our club. They could not remember what they are or where they came from, but they could be from Arizona or somewhere in the Southwest US as they spend their winters in Arizona and always come back with stuff from collecting and wheeling and dealing down there. The bigger piece especially looks like oncolites to me, but I have been fooled before. Does anyone recognize either of these, and more importantly where they might be from? (If I can figure out the location I'll have a better chance of tracking down the ID/age.) Both pieces came already polished on one side. Smaller one has scratches. I tested both with vinegar and the larger one fizzes. (It would not fizz on the polished surface, but on the rough edge it did). The smaller one did not noticeably fizz. I thought it looked fossily but obviously different from the bigger one, so it might have been from a different chunk from the same site or it may be completely unrelated. Maybe not even sedimentary. The little 'bits' in the smaller piece seem to have crystalline interiors but surrounded in the same type of reddish 'buildup' that the oncolites(?) in the larger piece have. I'm not really expecting a decisive answer (I've not been too lucky in getting mystery items confidently ID'd lately, from the forum or otherwise... I seem to have a knack for digging up strange things). But I thought I would survey the forum in the off-chance someone recognizes the material. A Google image search did not turn up a perfect match for either. The color balance in my photos may be a bit off (indoor lighting), but it's the best I could do for now. I could try direct sunlight tomorrow. Side-by-side comparison of both pieces: Weathered edges (smaller piece on top) - the greyish patches could be either paint or rock saw sludge, it won't come off easily:

I showed some of this material to a geologist and licensed gemologist to verify what it is, and he said most is agate in some form, and that a lot is petrified wood. I didn't know we had petrified wood up here. The longitudinal grain seems to be clearly defined, and gives a nice striped pattern. The cross-section cuts give sort of a cloud agate appearance. The large "logs" are in the softer stages. They are composed of powdered phyllite mixed in with sand and mica. The mohs hardness is about 3.5. The teal blue striped material in the video is an example. The quartz petrified wood is mohs 7 and quite brittle. Can anyone identify tree species? Chestnut was abundant at one time. Blue quartz w/ petrified wood (below) Grayson County, VA White Top Mountain Rhyolite: Petrified wood cross-cut on diameter: Petrified wood lengthwise cut on lower right: Petrified logs (some are soft): Watauga County, NC specimens:

Hi All! I found what looks like petrified wood near Burro Creek near Wikieup Arizona. There is a lot of rhyolite in the area as well. It looks tree-ish but just looking for an ID either way.

A close-up look at an uncommon underwater eruption January 10, 2018, Woods Hole Oceanographic Institution http://www.whoi.edu/news-release/a-close-up-look-at-a-rare-underwater-eruption https://phys.org/news/2018-01-close-up-uncommon-underwater-eruption.html https://www.sciencedaily.com/releases/2018/01/180110141320.htm The paper is: Rebecca Carey, S. Adam Soule, Michael Manga, et al., 2018. The largest deep-ocean silicic volcanic eruption of the past century. Science Advances 10 Jan 2018: Vol. 4, no. 1, e1701121 DOI: 10.1126/sciadv.1701121 http://advances.sciencemag.org/content/4/1/e1701121 A related and interesting paper is: Simkin, T., 1993. Terrestrial volcanism in space and time. Annual Review of Earth and Planetary Sciences, 21(1), pp. 427-452. (Volume publication date May 1993) https://doi.org/10.1146/annurev.ea.21.050193.002235 http://adsabs.harvard.edu/full/1993AREPS..21..427S Yours, Paul H.