Linarite, a beautiful blue mineral

Linarite is somewhat rare mineral with an intense deep blue color. It is a combined copper lead sulfate hydroxide mineral, which is made of up flat (monoclinic) crystals that are soft (hardness of only 2).

The specimen shown here is one that I collected back in 1964, when I was an undergraduate geology student. The specimen is from the world famous Blanchard Claims in the Hansonburg Mining District, Sierra Oscura Mountains, south of Bingham, New Mexico. When I visited the site, Ora Blanchard was the caretaker. I remember her as a very colorful character. She did not take kindly to thieves trying to sneak onto her property. She wore a pistol, and she also had a flock of geese to serve as "watch dogs."

Mrs. Blanchard allowed me to collect in the famous Royal Flush mine. The linearite crystals occurred with galena, aquamarine-colored fluorite, bladed barite, and druzy quartz, among with many other minerals. The rock matrix is the Pennsylvanian-age Madera Limestone, which was invaded by hydrothermal fluids (about 200°C) emanating from the nearby Rio Grande Rift. Supersaturated fluids moved along any open space and deposited beautiful crystals of the minerals, including linarite.

linarite hand specimen, length 7 cm (2.75 in.)

Mariposite from California

Mariposite is not an officially classified mineral, rather it is a chromium-rich variety of the green mineral phengite. The green color is imparted by the element chromium. Mariposite/phengite occurs in a quartz-rich metamorphic rock also called mariposite. This rock, which is streaked with thin bands of green color alternating with bands of grayish quartz, is named for its occurrence in the southern-most part of the “Mode Lode” (i.e., gold) region northeast of Merced and southwest of Yosemite Valley in Mariposa County, Northern California. Mariposite is associated with gold-bearing quartz veins and has been reported as occurring with visible gold.  

Mariposite rock, length 7.5 cm (3 in.)

Mariposite formed when the rock serpentinite, which was derived from the Earth's mantle, became altered under pressure by mineral-laden hot (650°F) water. These hydothermal fluids flowed upward along fractures, faults, and fissures, and where these fluids reacted with serpentine, they formed deposits of quartz, chromium-rich mica, sulfides, and gold.

Mariposite is a popular landscaping stone. It is also used as a building stone (veneer on walls), as well as for jewelry (as the trade name "Emerald Quartz).

A cut and polished mariposite stone (length 3 cm, 1.2 in.)

The large shallow-marine gastropod Forreria belcheri, past and present history

Forreria belcheri (Hinds, 1843) is a rather large gastropod found today along the west coast of Southern California and Baja California, Mexico. Forreria belongs to the family Muricidae, commonly referred to as the "rock shells." Forreria belcheri is the type species of genus Forreria.

This gastropod has a fossil record that extends back about 8 million years to the late Miocene. In the past, it ranged farther north (to central California) than it does today. It lives today mainly offshore on sandy bottoms in relatively shallow water of 60 to 100 feet deep, but it can also be found in bays, lagoons, and mudflats. This gastropod is carnivorous and uses its file-like radular teeth to drill holes through shells of oysters and mussels, as well as other mollusks. 

Forreria belcheri is characterized by a large, heavy shell that can be as much as 6 inches (15 cm) long. The shell is heavy and adult specimens have about 12 spiny nodes on its whorls. Its opening (aperture) is large and the anterior end of its shell is twisted and upturned. 

The first two views in the below series of photographs show the front (apertural) side of a modern specimen from Baja California, Mexico versus a Pleistocene specimen from Newport Beach Mesa, Southern California. The last two views of this series show the back side (abapertural) of the same modern and Pleistocene specimens, respectively.

Forreria belcheri: A modern specimen (13 cm height) vs. a Pleistocene specimen (11.6 cm height).

The next two views show the spatial arrangement of the spiny nodes on the spire whorls of the same two specimens: Modern specimen (on left) vs. Pleistocene specimen (on right). The Pleistocene specimen is somewhat worn and has its lower right-hand spire coated by bryozoans.

This last view, which is of the side of the modern specimen, shows how the twisted anterior end also turns upward (a characteristic feature).