Quartz

Quartz (マイカ Mica) is a Venus Djinni found  throughout the Golden Sun  series.

Quartz is the third Venus Djinni in the original Golden Sun, and can also be  acquired in Golden Sun: The Lost Age. Although it is not the party's third Venus Djinni in The Lost Age, Quartz is still ordered as the third  Venus Djinni when equipped to characters. Because it is not available until after most other Venus Djinn can be found, however, the separate  Djinn list viewable with the Select button from the status screen lists  Quartz and all other Venus Djinn from Golden Sun after all of the  Djinn introduced in The Lost Age. According to this order, Quartz is the fourteenth Venus Djinni in The Lost Age rather than the third, but this order has no influence elsewhere in the game.

In Dark Dawn, Quartz appears as one of the "extra Djinn" in the  Djinn Guide because of its temporary appearance in the earliest  stage of the game.

Basic description
When Set, Quartz increases its Adept's base HP by 10, base PP by 3, and base Agility by 3.

When Quartz is unleashed in battle, the selected Downed Adept has a 50% chance to be revived, and their HP restored to 50% of their maximum HP.

In Golden Sun and The Lost Age, Quartz's unleash  animation visually resembles the user summoning a glowing, transparent  image of a Venus Djinni that hovers above the party briefly, then the same visual as the Revive Psynergy - several glowing yellow images of feathers float down to the target's position, and then the target is engulfed in a vertical beam of yellow energy briefly. In Dark Dawn, when the user summons the 3D model of Quartz, the field and background turns black, and while there are no glowing feathers that fall down above, the vertical beam looks very similar as to the GBA games, though this time the beam shoots straight down from above very quickly.

Locations
Golden Sun: Quartz is located late in Mogall Forest. In a screen you enter down from the top end, to the right of the screen is a rock right below a horizontal log - position yourself above the log and use Move to move the rock down one space into the circular indenture in the ground, then push the log down. Push a second horizontal log down, push the vertical log from the right to left, and go down and left to reach  the Djinni. It must be battled to be acquired.

Golden Sun: The Lost Age: Players can transfer data from Golden Sun to The Lost Age, but  even if they don't, Quartz will be among the Djinn Isaac's party has  with them when they join forces with Felix's party late in the game.

Golden Sun: Dark Dawn: Quartz is one of the five Djinn that Isaac  and Garet keep to themselves and exclusively use while in Tanglewood,  meaning that the player can only see Quartz being used while exploring Tanglewood, the  Abandoned Mine beyond that, and the Tangle Bloom boss fight at  the end. After this, Quartz and the other Djinn are not seen for the rest of the game.

As an opponent (Golden Sun)
Statistically, Quartz has 349 HP, 25 PP, 127 Attack, 28  Defense, 76 Agility, and 9 Luck when it is fought in the first game. Like all other Venus Djinn that are fought, in terms of resistance, it has a Venus Resistance  rating of 193, Mercury and Mars Resistance ratings of 100 each, and a  Jupiter Resistance rating of 25, and in regards to its abilities it uses  its available Venus-based attacks with a Venus power rating of 125.

Quartz can use the following battle commands:
 * Earthquake: Used 53 out of 256 times, this is a Psynergy spell that prompts  three rectangular sections of ground underneath the party to jolt upward  and retract into the ground quickly twice in succession, bouncing each  Adept twice. It dealing a Veus-based attack with a power rating of 35  and a range of 5. This ability consumes 7 of its user's PP.
 * Spire: Used 47 out of 256 times, this is a Psynergy spell that causes a thick  stalactite to fall out of the sky and shatter onto a target, dealing a  Venus-based attack with a power rating of 40. This ability consumes 5 of  its user's PP.
 * Gaia: Used 41 out of 256 times, this is a Psynergy spell that causes the ground beneath the enemy  to open up and engulf the party in a wide reverse shower of Venus  energy and medium-sized boulders, dealing a Venus-based attack with a  power rating of 40 and a range of 3. This ability consumes 7 of its  user's PP.
 * Mad Growth: Used 35 out of 256 times, this is a Psynergy spell that causes a group of thorny vines to  erupt from the ground and through the Adepts for a short time, dealing a  Venus-based attack with a power rating of 60 and a range of 3. This  ability consumes 10 of its user's PP.
 * Briar: Used 29 out of 256 times, this is a Psynergy spell that causes a series  of quite large spiked vines to grow out of the ground quickly to assault  the opposition, dealing a Venus-based attack with a power rating of 70  and a range of 3. This ability consumes 11 of its user's PP.
 * Attack: Used 28 out of 256 times, this is this monster's standard physical attack, but for this monster it is counted as a  Venus-based attack rather than a non-elemental attack.
 * Flee: Used 23 out of 256 times, this enemy has the ability to attempt to Flee  the battle, thereby ending the battle if successful without rewarding  you with the associated EXP, Coins, and the Djinni itself, and the Venus  Djinni disappears from its field spot. If this happens to you, you  should walk back up out of the top of the screen and reenter, and  re-solve your way to Quartz' position.

When defeated, Quartz yields 172 EXP and 201 Coins, and the Quartz  Djinni is added to your party's Djinn collection. If you fell it with an offensive Jupiter Djinni like Gust, its rewards increase to 223 EXP  and 261 Coins.

It is possible to have three Jupiter Djinn in your collection at this point,  so having Ivan summon Procne with them will deal over 200 damage to  Quartz in one blow - from this point onward, it becomes easy to defeat  and earn Djinn because of the amount and power of summons you can unload  in the beginning of a battle.

Analysis
General: Quartz is the least useful reviving effect in any of the games it appears in because there is only a 50% chance that a revive can occur, and even when a revive occurs it is only to 50% of the maximum HP meter. Other Djinn have both much higher chances to work and restore much higher percentages of HP, as well as the Revive Psynergy and the Water of Life item, which have a 100% chance to revive to 100% HP.

By game
Golden Sun: Early in Golden Sun, Quartz can be potentially very useful as a means to try to get a downed Adept alive again if you don't have/want to use a Water of Life, even though that item is guaranteed to work and restores the Adept to 100% HP. Once the Revive Psynergy starts becoming available to Adepts at level 19, however, this Djinni's battle effect becomes immediately obsoleted, because Revive  has the exact same properties of the Water of Life - guaranteed chance  to revive at 100% HP, and may be used both outside and inside battle,  for "only" 15 PP. Revive is a staple that is pretty much always used  over not just Quartz, but its later superior counterpart, the Mercury  Djinni Dew (which revives to 80% HP at an 80% chance).

Golden Sun: The Lost Age: When Isaac's party joins Felix's party along  with their returning Djinn, Quartz's ability (and Dew's, for that matter) is all the more inferior  as an in-battle reviving option because in addition to Revive being used  as often as ever, there are other Djinn with better reviving effects,  like the Mars Djinni Tinder that guarantees revival to 100% health, and the Mercury Djinni Balm which has a 60% chance to revive all downed Adepts in the currently battling party to 60% maximum HP each.

Golden Sun: Dark Dawn: Quartz is Set on Isaac at the earliest stage of the game, and the computer-controlled Isaac will use Quartz if  either Matthew or Karis are downed at any point - though there is a good chance that Quartz will fail on the Adept it is intended on. This is directly inferior to Spark, the Mars Djinni that is temporarily loaned to Matthew and Karis during the same opening segment, because Spark heals 10% more HP and has an additional 10% accuracy. Perhaps the "downside" to Spark here is that you would have to use up one of your two controllable Adepts' turns for it, and Spark can't be used if it's the Adept that it is set on that is Downed. Even granting that the earliest stage of the game grants two separate inaccurate reviving Djinn, neither of these are necessary effects because the boss encounter with the Tangle Bloom at the end is impossible to lose. In the main game, the Jupiter Djinni Jolt is this Djinni's identical equivalent.

Name Origin
Quartz is a type of crystal commonly found in the Earth's crust. Mica is a silicate mineral with a layered structure, often found as minute scales in granite and other rocks, or as crystals.