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2" Rock Measurement. Orange/Amber area in middle is 1.5".

The closest most clear image I could capture.

NEW EDIT. I took a sharp knife and scratched at the orange/amber area. The area the blade tip went across would develope a faint white mark; however if I licked my finger and wiped the mark it disappeared with no visible scaring or trace. I attempted to mark the rock at various pressures until I was pushing so hard knife would skip and I stabbed into the wood work bench a 1/2". No matter the pressure results were the same.

Old..... I founde digging through piles of river runoff dirt/rocks that were removed after flooding from farm land. It was originally located in Central Iowa, Story County, USA.

In natural light the Orange/Amber color appears much brighter. Stone is wet from washing. Pictures are of the front (2); then the back (1).

I am new to this but believe it is something inside quartz. Please help educate me!

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  • 3
    The whiter bulk material looks like quartz, but the pictures are out of focus to be able to identify the smaller other "orangey stuff". – Fred Dec 6 at 15:26
  • I will attempt to take a more clear picture once I return home. Thank you. – Shalene Dec 6 at 16:05
  • And please check this to improve your question – Jan Doggen Dec 6 at 16:24
  • Jan thank you. I got lost trying to find the help page before posting. Once home I will repair the post. Thanks again. – Shalene Dec 6 at 19:49
  • 1
    Don't be disappointed if the orangey stuff also turns out to be quartz. The translucency around the edges of the orangey area makes me suspect that it's just staining. – Spencer Dec 6 at 23:59
up vote 0 down vote accepted

Its likely feldspar in quartz, likely potassium feldspar by color (image below). Feldspar and quartz are often found together, it should be softer than the quartz but still harder than most steels but not harder than harder steels like file steel, sadly using a knife can be troublesome in this range since modern knives vary wildly in hardness. Feldspar ends up with flat cleavage while quartz is irregular (aka has no cleavage) which matches your image. enter image description here

  • Looks spot on. Thank you for the information and guidance. I plan to research further and learn more! – Shalene Dec 8 at 15:14

I believe you have a fossilized Crinoid calyx. These are animals related to starfish (echinoderms) and are also called feather Stars. They were/are filter feeders and have a calcium carbonate skeleton. Technically, an endoskeleton. Iowa was near the equator and was covered much of the time by warm, shallow inland seas 300-400 mya. Generally the crinoids of this time (ordovecian, Devonian, Mississippian eras) were composed of 3 main parts: the calyx, a central, main body that contained the digestive organs, nerve and water vascular systems. It was composed of one to three series of 5 calcium carbonate plates. From this central calyx sprouted arms that branched out to varying degrees depending on species. Together the arms and calyx made the crown. The ccrown was attached to a column made of calcium carbonate discs held together by ligaments and an encapsulating membrane. Together this is called the stalk. The stalk terminated in root or spade like appendages called holdfasts. Upon death, the different parts typically disarticulated upon disintegration of the soft tissue. Typical finds of fossilized crinoids are just the calyx--or even just the plates of the calyx--the discs that formed the stalk (aka: coloumnals), and then the holdfasts. Here's a link with far clearer information on these creature's: http://www.fossilcrinoids.com Coincidentally, I reside in Cerro Gordo County Iowa and work for an excavating company. I have found lots of interesting, colorful rocks. I believe this is a crinoid calyx because it has the distinct shape-- some what of an oval with one side being more favored to triangular. In the second shot (I believe) there is a district triangular shape in the calyx's central area. I'll attempt to attach some pictures of my finds. Looking forward to hearing other opinions regarding these enter image description hereenter image description hereenter image description hereenter image description here

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Jeff is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct.
  • 1
    What makes you think that is a fossil and not a rock, fossils are not commonly found in massive quartz. Your linked images don't look like crinoids or even fossils at all. – John Dec 8 at 14:48
  • I am not 100% sure. The details such as suture lines between plates have weathered and are not clear to the naked eye as in a more pristine specimen. However, I maintain these are in fact crinoid calyx that have undergone petrifaction, with permineralization to quartz, calcite, pyrite, siderite, apatite, etc. The 4 pics are all different specimens yet share the same general shape, pentaradial symmetry can be seen, and each side of one specimen can be closely matched in shape, structure and detail to the correlated side of the others. See also references such as "North Am. Crinoids" – Jeff Dec 8 at 16:30
  • I believe that the four pics coincidentally each show views of the tegmen of the crinoid. Zooming in on a photo can reveal vestiges of arms, especially in #1, 3, 4. Individual plates forming the cup can clearly be discerned in #2 and 4. – Jeff Dec 8 at 17:37
  • In Shalene's images, individual plates (now quartz or calcite) can be discerned as well as the suture lines between them. Most evident in #1 of Shalene's specimen. Photo #2 the darker rock are stubs of arms and notable here just left of center, in the darker rock, is a cross section that reveals pentaradial symmetry. The mineral make-up could be SIDERITE: brown color, subtranslucent, white streak, tabular, striated faces, associated with sedimentary rock of shallow depth, and encompasses 3 dimensional fossils. – Jeff Dec 8 at 18:13
  • fossilization does not result in just any mineral, it is specific water soluble mineralization. the images don't show pentaradial symmetry they show planes of weakness and fracture patterns. There are not plates in your images plates have segmentation and a uniform shape. I applaud your enthusiasm but you do not have any fossils in the images posted. – John Dec 8 at 23:29

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