Museum Main Lobby
www.Lockport-NY.com
Because of the size of pictures on exhibit, load times may
be long.
The images should be finished loading by the time you finish reading the commentary.
Calcite crystals are reasonably easy to find in freshly quarried Lockport Dolomite but deteriorate fairly quickly when left exposed to the weather (5-10yrs.) Calcite is usually found lining small cavities (called vugs} in the dolomite rock. It is in these vugs that most of the other harder to find minerals also may occur.
The specimen at left is was recovered from the Frontier Stone Quarry
at Lockport. It is on permanent loan to our cyber museum from the New York State
Schoellkopf Geological Museum.
Calcite is the commonest form of carbonate and forms when the element, Calcium, combines with the Carbonate radical. Calcite makes up the bulk of limestone and limestone is commonly found in the Lockport area.
Calcite will effervesce when treated with cold, dilute, Hydrochloric Acid. This is a common field test for identification confirmation.
Calcite is a semi-hard mineral, ranked "3" on a scale of 1 to 10 with diamond at 10 being the hardest.
This
is an unusual specimen found in the old Frontier Stone quarry near Ohio Street in
Lockport. What makes it unusual is the doubly terminated calcite crystals forming on
and around the darker sphalerite crystal.
Sphalerite is zinc sulfide with some iron substituting for in zinc. The iron gives the brown color to the crystal.
Sphalerite can be found also in black, yellow, red, green, grey and even white. It varies from translucent to transparent. It is ranked about "4" on the hardness scale.
A test to confirm Sphalerite is simple because of the sulfide content. Dilute Hydrochloric Acid is added to a sample and the smell of hydrogen sulfide ("rotten eggs") is immediately noted.
Gypsum is quite a common mineral in Lockport Dolomite and in Rochester shale with the clear single form, known as selenite, occurring in Lockport dolomite. Occasionally, it will fill a vug containing other minerals so the other crystals are visible through the transparent selenite. In Rochester shale, it occurs primarily as fine grained lumps which are relatively unconsolidated. After a very short time out in the weather they fall apart on their own.
Shown is the "Selenite" variation of Gypsum.
Gypsum is in the Sulfate group of minerals. It is known as Calcium Sulfate
with two parts of water in content.
Gypsum is relatively soluble in water compared to other minerals found in
Lockport dolomite and Rochester shale. Selenite is quite a soft mineral
("2" on the hardness scale) and can be marked using a fingernail, so care must
be
taken if a specimen found is to remain in good condition. Selenite has a strong
cleavage in one direction revealing large flat surfaces as seen here.
Click Here To
Go On To The Next Mineral Gallery
Lockport's Service Site On The
World Wide Web
www.Lockport-NY.com
THE PICTURE OF LOCKPORT