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Graphite crystal in pink matrix????

Posted by Massimo B.  
Graphite crystal in pink matrix????
June 26, 2012 03:25PM
Hi all

I found this rock in a stream in Rockland County NY and stuck out half is been polished by the water I look around a dint find anything else,
I think the small crystal are Graphite soft to the touch for what I can understand can any one help me determine what is the pink matrix is ?
I cant find anything like in MINDAT database

thank you for your help

Massimo B.

soon I will have hardness test done and will post
Attachments:
open | download - A C1A_1496-001 PICCOLA.jpg (290 KB)
open | download - A C1A_1600 PICCOLA.jpg (324.5 KB)
open | download - C1A_1623.jpg (312.8 KB)
avatar Re: Graphite crystal in pink matrix????
June 26, 2012 06:10PM
ca    
My first thought from the picture is that the blebs might be pyrrhotite rather than graphite but will wait for your hardness results. Can you also do hardness on the pink material? Is there a way to remove a small amount of the pink material that you could test in HCL to rule out carbonates? Also, there looks to be a yellow weathered coating on the whole piece?

good luck,
stephanie smiling smiley
Massmo Boccia
Re: Graphite crystal in pink matrix????
June 27, 2012 01:03PM
HI Stephanie


Thank you for your help
I did made a mistake I wanted to post in the "help identity help board"

the pink matrix have a white streak and hardness more than 2 and less than 3 tested with " minerallab mohs kit"

here are some more up close picture
the Graphite look like mineral have a white streak as well feel soft to the touch can be broken off with nails
Attachments:
open | download - IMG_1206.jpg (171.7 KB)
open | download - IMG_1205.jpg (96.2 KB)
open | download - IMG_1202.jpg (104 KB)
Re: Graphite crystal in pink matrix????
June 27, 2012 01:32PM
ca    
Massimo: Those crystals are "biotite" mica (probably phlogopite). There are also small prisms of diopside in your sample. The matrix is calcite.
avatar Re: Graphite crystal in pink matrix????
June 27, 2012 02:37PM
ca    
Yes , now with the close ups and more info I agree with Philip, they are mica, and yes saw the diopside crystals as well and therefore assumed the matrix was calcite and so that is why I suggested the HCL test.

It is a very pretty sample! Hope you find more.

regards,
stephanie smiling smiley
Massimo Boccia
Re: Graphite crystal in pink matrix????
June 27, 2012 02:52PM
Hi Phil

you are correct you know minerals...
I did do a search and found out exactly similar minerals , then I looked on the locality and found minerals with same characteristics in the same region not far from where I collected mine see picture.
this rock some how endup in the stream and got eroded by water


and this below are the stats for the picture i attached.

No. 50228
Mineral: Diopside and Scapolite in Calcite
Locality: Route 6 Road Cut, Bear Mountain State Park, Orange County, New York
Description: Irregular green-black diopside crystals to 12 mm long with translucent colorless scapolite crystals to 4 mm in translucent orange calcite that was partially dissolved to expose the crystals. Ex. Peter B. Nalle (1923-2010) collection #751; collected by Ex. Harold Uhlin (1914-2000) ca. 1970
Overall Size: 4x4x2 cm
Crystals: 1-12 mm
Status: SOLD Buy similar at: Minerals from New York & New Jersey, USA > Feldspar, Mica & other Silicates
Counter: #50228 viewed 122 times
Attachments:
open | download - 50228det.jpg (45.4 KB)
Massimo Boccia
Re: Graphite crystal in pink matrix????
June 27, 2012 03:04PM
HI Stephanie

thank you for you help
there was this rock in a near by location you suggest i go back and collect it?
look at picture let me know if it is worth is a hike to get there


Thank you
Massimo
Attachments:
open | download - IMG_0827.jpg (273.4 KB)
open | download - IMG_0826.jpg (222.7 KB)
avatar Re: Graphite crystal in pink matrix????
June 27, 2012 03:16PM
Hola Massimo,

The dark hexagonal material really looks as biotite mica.

Relating the pinkish matrix, are you sure about hardness? To me, it looks as feldspar. Calcite and mica are not common paragenetic species. To me, the whole piece looks as a granitoid rock composed by feldspar (mostly), quartz (few) and biotite.

Just a thought...

Josele
Re: Graphite crystal in pink matrix????
June 27, 2012 06:41PM
Jose,

In the Grenville rocks there is a characteristic paragenesis of pink calcite+phlogopite+F-apatite+diopside (and a lot of other minerals).
avatar Re: Graphite crystal in pink matrix????
June 27, 2012 08:18PM
Massimo,
I am very with the geology of the Highlands region in Rockland/Orange County in NY. The pink matrix material is salmon calcite and is similar to the salmon calcite at Franklin. Just put some strong acid on it (i.e. such as lime out) and you'll see it effervesce. The dark green to black material is diopside, the small white crystals are scapolite, and the mica is biotite. There are also reports of small crystals of brown titanite in the area.

This comes from a skarn zone in Harriman State Park near Lake Massawippa and the Twin Lakes in Orange County, NY. The skarn zone runs across the valley called Brooks Hollow, in which those lakes lie. There is also a state-run camp in the area. Here is a mineral from the same skarn zone, which I photographed from the display in the Bear Mountain Museum, which is very close by: http://www.mindat.org/photo-440163.html. (I think this was taken from the dam construction by Route 6 by Lake Massawippa but the label doesn't state that specifically.)
avatar Re: Graphite crystal in pink matrix????
June 27, 2012 11:27PM
Ooops! thanks very much Eric.
Is a nice calcite, then. I didn't knew nothing about this region, sorry for confusion.

Josele
Re: Graphite crystal in pink matrix????
June 28, 2012 01:34AM
ca    
I have to disagree with some of the posts here.

- There appears to be no scapolite - the diopside is the greyish prisms (could be something else, but diopside is most likely. A close-up would help).
- Could easily be from marble rather than skarn.
- Most likely occurred in the direct vicinity (1-2km) of the area and even more likely the immediate area (within 50m), but a locality can not be assumed (I would NOT say it is from a specific skarn zone somewhere. Geological settings for this material are aplenty in the area).

Your other rock photo is of weathered granite. Not worth bringing home.
avatar Re: Graphite crystal in pink matrix????
June 28, 2012 03:43AM
Feel free to disagree, but I know the area well. I hike the area on a fairly regular basis and study the geology as I hike the different areas of Harriman State Park. The white material (or somewhat off-white) is scapolite. It is the meionite type. The diopside is very dark green, almost black, and occurs in small crystals or larger distorted crystal groups. The pink/orange calcite is metamorphosed marble in a skarn zone in the Precambrian Hudson Highlands rock. It is possible that from another geologically setting nearby, but unlikely due to the almost exact similarity between other minerals that were once found there. I guess we can determine this from the one who discovered this piece: Massimo, where is the exact spot where you found this material - was it in very close proximity to the lake right near Route 6?
Re: Graphite crystal in pink matrix????
June 28, 2012 06:35AM
pl    
Phil,
Blue crystal above mica (phlogopite) looks like scapolite [www.mindat.org]
Re: Graphite crystal in pink matrix????
June 28, 2012 01:22PM
ca    
Blue scapolite crystals are exceedingly rare. Apatite would be more likely in my opinion. The crystal is not well exposed so it is difficult to see the crystal system.

Hershel: I am in the nearby Grenville Province (S. Ontario / SW Quebec). I've done 9 years of mineral collecting, including much exploration for mineral occurrences in the past 4 years. I have explored in the forest, shallow lake bottoms and in construction sites. I can tell you that in some areas, skarns are very common (as are marble containing calc-silicate minerals), and skarns are usually very localized* (though some skarn systems can be few km wide) and extremely abundant. I have seen specimens come from new locations (exposed in blasting) that are identical in habit and geological setting to specimens from 5km away. If someone were to see some of the samples without a label, some would think it is safe to assume locality X, when that is wrong. Unless the sample habits/chemistry/association are extremely unique, it is not safe to prescribe it a locality.

*One area at an igneous contact had a number of skarns. Each were small (less than 4 m) and varied in composition: Some were rich in tourmaline, others in spinel, apatite, phlogopite, sulphides, or clinopyroxene. These changes were all seen within 300 x 60 x 20 m.



Edited 2 time(s). Last edit at 06/28/2012 01:44PM by Phil M. Belley.
Massimo Boccia
Re: Graphite crystal in pink matrix????
June 28, 2012 02:14PM
HI Hershel Friedman

thank you for your help and explanations now that I learned a little more about the region I realize I have few more similar samples
I find my self always picking up rock when I hike... i have couple crate full of it from all over
I just starting learning the identification process.

the second pictures of the rock I did not collect is not close to route 6 is is actually up on hill off Harden Valley road closer to route 17

the sample in question I collected @ silver mine across from pick-nick area in the little stream, it looks like they dumped some material there some time ago

@Phil .....I will try to take better picture of the blue crystal in the calcite matrix and test for hardness will post later on
avatar Re: Graphite crystal in pink matrix????
June 29, 2012 02:49AM
Hi Massimo,
My comment was regarding the first pictures you posted - the one from the Silvermine Lake Picnic area. I was actually right there a week and a half ago on a hike. Next time I go there I'll take a look in the stream over there. My suspicion is that it was deposited from the location I describe, which is about 4 miles away, and is not part of the native rock. But I am still certain it is salmon calcite with diopside and scapolite. Did you find it in the stream closer to the lake or on the other side at the end of the picnic area?

The other pink mineral, the one you found of Arden Valley Road, looks different. I can't tell forsure but it does look like feldspar. Did you find it close to Island Pond?
Re: Graphite crystal in pink matrix????
June 29, 2012 11:10AM
not near the lake, but up on the hill maybe 1/2 mile away from there wow you do know the area well...

I was planning to take a hike there tomorrow morning
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